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2 VS SDLT 320 | Drive
Technology Comparison
9 TO
5 COMPUTER: Global Value-Added Distribution
of NEW, used and refurbished computer
periphery by a family-owned and operated
company since 1979- distributing internationally
computer related peripherals on the new,
used and refurbished levels. HP|Computer Parts,
COMPAQ,
IBM,
CISCO,
3COM,
SUN,
APPLE,
SEAGATE,
and other major branded products as well
as a MAJOR focus on Mass Storage related
drives, media, storage
racks, tri-optic
barcode labels, libraries, autoloaders,
duplicators,
jukeboxes,
HBA's,
JBOD,
Raid, SAN,
NAS and software
solutions.
Quarter-Inch
Cartridge (QIC) | O-MaSS | Minicartridge
| DLTtape | Super DTLtape (SDLT) | Linear
Tape-Open (LTO) | Half-Inch Cartridge |
StorageTek 9840/T9840B/T9940
Helical-Scan
Technologies | 4-mm
Helical Scan Digital Audio Tape/Digital
Data Storage (DAT/DDS) | 8-mm
Helical Scan | Mammoth
Technology | VXA
Technology
Advanced
Intelligent Tape (AIT) Technology | S-AIT
Technology
Basics
Mainstream tape technologies are aligned
within two camps-linear and helical-scan
recording. The
debate over which technology is better suited
to safeguard an organization's valuable
data assets usually
centers on reliability, compatibility, capacity
and performance. Each technology claims
advantages over
the other in each of these critical metrics,
when in fact both technologies are well
suited to meet the
requirements of a majority of computing
environments.
Linear
Technologies
Linear tape-recording technology has been
in use since the early stages of computing.
Initially it was used
as a primary data storage medium. As storage
requirements changed, however, it was replaced
in this
role by hard disk drives, which provided
the advantage of random access capability.
Linear tape then
began to be marketed as a secondary storage
medium. Over the years, linear tape technology
has
evolved in all key areas-capacity, performance,
reliability and cost-and remains the leading
secondary
storage device for today's computing environments.
Quarter-Inch
Cartridge (QIC)
Quarter-inch tape technology was introduced
more than 25 years ago, and although market
share has
declined in favor of new formats that yield
higher capacity and performance, QIC still
accounts for a large
installed base of primarily smaller networked
and stand-alone environments. The format
has evolved into
higher-capacity implementations and has
established standards for backward compatibility
that have kept
the technology alive.
QIC tape drives use media that is 0.25 inch
or 0.315 inch wide with varying lengths.
The widening and
lengthening of the tape were the developments
that contributed to moving the technology
to new
capacities. Data is recorded in a linear
serpentine fashion along parallel tracks
that run the length of the
tape. QIC tape cartridges contain two reels,
one for tape supply and the other for tape
take-up. The
mechanism that drives the reels as well
as the tape guide path is internal to the
removable cartridge.
Tandberg Data became the sole drive manufacturer
in this segment in 1988 with its Scalable
Linear
Recording (SLR) technology, which the company
continues to develop for smaller or cost-sensitive
computing environments. With the introduction
of the SLR100 in November of 1999, Tandberg
Data laid
the foundation for its third generation
of SLR tape technology. The newer drives-the
SLR7, SLR60 and
SLR100-share a common hardware platform,
allowing SLR technology to scale in both
capacity and
performance while maintaining backward compatibility.
Some of their common features include:
o
Read Channel-The SLR7, SLR60 and SLR100
drives use a Partial Response Maximum Likelihood
(PRML) read channel and Variable Rate Randomizer
(VR2) technology. Tandberg Data and
Overland Data announced a cross-licensing
agreement in April 1998 that made Tandberg
the first
company to license Overland's VR2, which
is a Partial Response Maximum Likelihood
(PRML) data-
encoding technology for linear tape drives
designed to increase the capacity and performance
of a
product or technology by a factor of 1.5
to two times.
o
Multi-Channel Thin-Film Magneto-Resistive
Head (TFMR)-The SLR100 and SLR60 both use
a six-
channel TFMR head. The SLR7 supports a two-channel
TFMR head that writes two tracks at the
same time. The use of TFMR head technology,
coupled with VR2 encoding techniques, doubles
the
tape capacity when compared with previous-generation
SLR drives.
o
Dedicated Servo Tracking-The SLR100 and
SLR60 utilize a servo-based track-following
system.
The dynamic real-time servo tracking allows
the drive to reliably record and recover
data at high track
densities.
o
Auto-Sense-The SLR100 and SLR60 support
auto-sense features that assist in performance
optimization. Auto-sense will automatically
adjust the drive's speed based on the average
data
transfer rate from the host to the drive's
buffer. Optimizing the transfer rate helps
to keep the drive's
data buffer full and the tape moving at
a constant speed, thus minimizing the number
of times that the
drive must stop and reposition itself before
resuming read/write operations. In those
instances when
the data transfer speed from the host does
fall below the minimum transfer rate for
the drive, the
drive will empty its buffer while quickly
repositioning itself at the same time so
it is ready to resume
write operations once the host fills the
drive's buffer.
o
In-Line Data Compression-Data compression
technology used in Tandberg's SLR drives
is based
on the ALDC (Adaptive Lossless Data Compression)
algorithm. The SLR100, SLR60 and SLR7 all
support an updated compression scheme called
in-line compression, which allows data to
be
compressed before entering the drive's 8MB
buffer, thereby minimizing backup and restore
times. By
using a separate data compression path,
100 percent of the drive's buffer can be
used for storing
data prior to being written to tape.
These core technologies will allow SLR technology
the ability to cover a broad range of backup
requirements and price points using highly
reliable and cost-effective technology,
including the potential to
develop SLR drives with native capacities
reaching 200GB. Tandberg Data also offers
an entry-level SLR
product line targeted at low-end workstations
(with native capacities ranging from 525MB
to 4.0GB).
O-MaSS
In addition to SLR technology, Tandberg
is also developing a new product based on
a technology it calls
O-MaSS. This new technology uses a matrix
array write head, which Tandberg has been
developing for
seven years, that enables writing much-denser
data and recording 32 tracks at a time.
It uses an optical
servo system and an optical read head. The
intent is to use standard media that is
available today that will
be housed in a half-inch cartridge similar
to that of LTO and DLT. But the tape will
be shorter and wider
with a width of 2.5 to 3 inches. It uses
a center-park, dual-reel design to provide
fast access times, and
the tape reels are oriented horizontally
inside the cartridge. It is also unique
in that the tape never leaves
the cartridge and the recording head goes
inside the cartridge during a read or write
operation.
With expected introduction in 4Q03, a first-generation
implementation is projected to store up
to 600GB of
uncompressed data on a single O-MaSS data
cartridge at data transfer rates up to 64
MB/sec. O-MaSS
pricing is expected to be comparable to
LTO Ultrium and Super DLTtape at product
introduction. The
company also claims that the O-MaSS technology
could be used by other tape technologies
to boost their
capacity and performance beyond those shown
on their current road maps.
Minicartridge
Drives in this category are based primarily
on Imation's Travan technology and Advanced
Digital
Recording (ADR) technology from OnStream
Data. Imation Corporation introduced Travan
in 1995 and
currently partners with Seagate Removable
Storage Solutions (RSS) to develop drives
based on this
technology. OnStream's technology has its
foundation in the Philips Digital Compact
Cassette (DCC)
audio tape player, which Phillips originally
brought to market in 1993. ADR was created
by leveraging the
DCC technology along with other research
and development that was done by Philips
Electronics.
Travan technology, which is based on linear
recording technology, is closely related
to quarter-inch
standards. It leveraged proven minicartridge
technology that existed prior to its introduction
in December
1994, and it maintained backward compatibility
with the installed base of drives. But it
did represent a
major advancement in the technology because
it was based on a unique drive/cartridge
interface
developed by 3M. At the heart of the new
technology was a new-shaped cartridge that
optimized the
amount of tape area for cartridges that
could fit in a 3.5-inch form factor tape
drive. Data is recorded along
the length of the tape with a static read/write
head, and drives use single-channel recording
and a simple
tape path with only two moving parts in
the drive. Unique to Travan drives is the
track-positioning system
with prerecorded servo patterns at both
ends of the tape. Through accurate electronic
servo signal
detection and digital signal processing,
the track-positioning algorithm positions
the head to the optimal
location relative to the data tracks on
the tape. When the read/write head is correctly
positioned at the
beginning of the tape, it is locked into
position. A precision tape guidance system
built into the Travan
data cartridge prevents the tape from wandering.
Seagate and Imation remain committed to
extending Travan technology capacity and
performance, and in
March 2002 the two companies announced the
availability of a new family of sixth-generation
Travan
drives, called Travan 40. This new technology
extends the native storage capacity to 20GB
(40GB with
2:1 data compression) with a native data
transfer rate of 2 MB/sec (4 MB/sec when
operating in
compressed mode) while maintaining backward
read compatibility with 10GB (native) Travan
20 drives.
The Travan 40 uses Seagate's FastSense technology,
which adjusts the speed of the tape drive
to match
system throughput. FastSense keeps the tape
in a streaming mode of operation, helping
to optimize
backup times. A number of other design enhancements
were also added to the Travan 40, including
a
steel frame for improved durability, a soft-load
mechanism to reduce normal wear and tear,
and a thermal
monitor that activates firmware throttle-down
features when drive temperatures reach perdetermined
levels. A VR2 data channel was also incorporated
to enable higher recording densities, and
a park feature
that ensures the alignment of recording
tracks if a write operation is suspended
was added.
OnStream's ADR is based on a variable-speed,
digital tape storage technology with two
distinguishing
features that differentiate it from competitive
technologies.
o
Spatially Distributed Error Correction Code
(ECC)-ADR makes use of spatially distributed
ECC,
meaning that error correction bits are recorded
over all eight tracks simultaneously so
information can
be recovered even if an entire track is
lost. OnStream rates the drive error rate
at one lost bit in every
1,019 bits written.
o
Full Tape Servo-An advanced embedded servo
system contributes to high data reliability
in two
ways: first by communicating with the head
to assure media integrity as it writes data,
and second by
preventing the tape from wandering off track,
which could make the data unreadable in
the future.
OnStream's second-generation ADR drive,
the ADR2 120Si, uses a SCSI-3 LVD/SE Ultra-2
compatible
interface and is positioned for use with
entry-level servers and workstations. It
supports 60GB of native
capacity (120GB with compression) and data
transfer rates up to 4 MB/sec (8 MB/sec
with 2:1
compression).
DLTtape
Digital linear tape is an adaptation of
the early generation reel-to-reel magnetic
tape recording method.
Developed by Digital Equipment and originally
used in support of its own computer systems,
half-inch
DLTtape drives were introduced to the client/server
and network-attached PC market several years
ago.
Quantum Corporation now owns the DLTtape
trademark, having acquired the technology
from Digital in
1994. In October of 1998, Quantum and Tandberg
Data entered into a strategic manufacturing
and
distribution agreement that made Tandberg
Data an independent second source for DLTtape
drives under
the Tandberg Data brand name, though the
specifications remain the same. In October
of 2001,
Tandberg Data extended its manufacturing
and distribution agreement with Quantum
Corporation. The
new agreement allows Tandberg to sell DLTtape
and Super DLTtape technology to distributors
and
OEMs that are headquartered in Europe, Asia/Pacific
and Japan only while U.S. and Latin American
markets would be left to Quantum.
DLTtape products use a single-reel design
whereby the tape cartridge contains the
supply reel and the
corresponding take-up reel is located in
the tape drive. Loading the tape is accomplished
by attaching a
leader strip to the end of the tape and
using that to pull the tape out of the cartridge,
around the head
guide assembly, past a stationary read/write
head and onto the take-up reel. This is
in contrast to helical-
scan designs, which have two reels per cartridge
and rotating read/write heads. The head
guide assembly
is shaped like a boomerang and features
six rollers that guide the tape along the
tape path, working from
the back of the tape so that they never
touch the recorded side of the media.
One disadvantage affecting some of the DLTtape
drives is the result of the leader mechanism
designed to
pull the tape out of the cartridge and wrap
it around the take-up reel. Under certain
conditions, the leader
can disengage, leaving the tape drawn partway
out of the cartridge but not successfully
engaged in the
drive. This renders the drive unusable and
the tape (with all its data) not repairable.
Quantum addressed
this intermittent problem in a revision
to its DLT 8000 product by expanding the
leader latch to allow more
room for airflow; however, previous models
(DLT 4000 and DLT 7000) were not refitted.
Both the DLT
4000 and the DLT 7000 have been marked for
end-of-life by Quantum. The phaseout for
the DLT 4000
was completed at the end of the third quarter
of 2001. Quantum, however, has opted to
continue selling
the DLT 7000 on a limited basis.
Quantum and Benchmark Tape Systems have
engaged in a partnership that allows Quantum
to focus its
development initiatives on SuperDLT enhancements,
while Benchmark focuses its efforts on improving
and extending the life of DLTtape. Through
a technology licensing agreement with Quantum,
Benchmark
has developed what is essentially a next-generation
DLT 4000, called the DLT1. The DLT1 is replacing
the DLT 4000 and DLT 7000 in the market.
DLT1 actually surpasses both products in
native capacity with
40GB (the DLT 4000 supports up to 20GB,
and the DLT 7000 supports up to 35GB) and
in fact actually
matches the DLT 8000. The DLT1 falls in
between the DLT 4000 and the DLT 7000 in
data transfer rate
at 3 MB/sec native data transfer rate vs.
1.5 MB/sec for the DLT 4000 and 5 MB/sec
for the DLT 7000.
DLT1 is read-compatible with the DLT 4000
and utilizes DLTtape IV media. Quantum's
Super DLTtape
drive will also read media written by Benchmark's
DLT1 tape drive. Benchmark's ValuSmart Tape
80 is a
repackaged DLT1 drive in a half-high form
factor. All capacity, performance, format,
reliability and
compatibility specifications are identical
with the DLT1.
In June 2002, Benchmark announced its next-generation
drive in the ValuSmart family, the ValuSmart
Tape 160. The new drive, which is expected
to become generally available by year-end
2002, will offer an
80GB native (160GB compressed) capacity
and an 8 MB/sec native (16 MB/sec compressed)
data
transfer rate, and will be backward read
compatible with the DLT1 and ValuSmart 80.
Super
DLTtape (SDLT)
The latest generation of DLTtape, called
Super DLTtape or SDLT, is based on Laser-Guided
Magnetic-
Recording (LGMR) technology, Quantum's name
for a conglomeration of features that together
facilitate
the increased track density and capacity
achieved with SDLT. This technology consists
of five elements.
The first is the Magneto-Resistive Cluster
(MRC) heads, a group of small magneto-resistive
heads that
are packed together to form a cluster and
are held in position using thin-film processing
technology.
Because the read and write heads are closer
together, the clusters are smaller than
previous head
configurations.
Second is SDLT's servo system-referred to
as the Pivoting Optical Servo (POS)-an optically
encoded
servo system on the back of the media that
frees up the front magnetic side of the
media to hold more
data tracks. As the tape media moves through
the POS, the optical tracking laser follows
the servo tracks
on the back of the media, tracking the embedded
optical targets. The POS assembly pivots
around a
single mounting point to keep the read/write
heads aligned with the optical servo tracks
and reading from
or writing to the tape. This method also
allows SDLT media to be bulk erased without
losing the
embedded servo tracks.
Third is advanced Partial Response Maximum
Likelihood (PRML), which Quantum developed
for Super
DLT in conjunction with Lucent Technologies.
Advanced PRML is based on technology commonly
used in
hard disk drives that allows for higher
encoding efficiencies and recording densities,
increasing capacity
and transfer rates. Advanced PRML offers
peak detect sampling that allows Quantum
to put data closer
together on the tracks.
Fourth is the media itself. The SDLT drives
use Advanced Metal Powder (AMP) media, which
has a
special coating on the back that allows
optical servo tracks to be located there.
Data capacities are
increased because the entire front side
of the tape is available for data tracks.
Furthermore, the AMP
media does not require pre-formatting.
Fifth is Quantum's Positive Engagement Tape
Leader Buckling System. The company replaced
the
previous leader latching mechanism, used
on the DLTtape line, with a new design called
the Positive
Buckle Link. The Positive Buckle Link uses
a solid metal pin on the drive leader that
hooks into molded
clips attached to the tape leader inside
the cartridge. This is different from the
DLTtape design, which
incorporates a hoop at the beginning of
the tape cartridge that mates with a "mushroom"
on the drive
take-up reel to pull the tape out of the
cartridge, through the tape path, and onto
the take-up reel. To
support backward read compatibility to the
previous-generation DLT products, however,
the Positive
Engagement Tape Leader Buckling System also
has a "mushroom" to enable SDLT
drives to load and
read DLTtape IV media. Quantum expects this
design to be even more reliable, especially
in highly
automated environments.
Super DLTtape is intended to be scalable
and will support a range of products targeted
at different market
segments. The industry's first SDLT drive,
the Quantum SDLT 220, is targeted at midrange
markets,
including large corporate departments and
midsize automated libraries, supporting
a native capacity of
110GB (220GB compressed with a 2:1 data
compression ratio) and a native transfer
rate of 11 MB/sec. It
comes in both backward read-compatible and
nonbackward read-compatible models. Quantum's
follow-
on product to the SDLT 220, the SDLT 320,
was released in June 2002 and takes Super
DLTtape
technology to the next level on Quantum's
Super DLTtape product roadmap. It features
a native capacity
of 160GB (320GB with 2:1 compression) and
a native transfer rate of 16 MB/sec or 32
MB/sec
compressed. The SDLT 320 is backward read
and write compatible with the SDLT 220 and
backward
read compatible with previous DLTtape models.
Linear
Tape-Open (LTO)
Linear Tape-Open (LTO) is an open tape architecture
that was developed jointly by a consortium
of three
vendors-IBM, Hewlett-Packard and Seagate.
It is made up of two specifications, LTO
Ultrium, which was
targeted for capacity-intensive applications,
and LTO Accelis, which was designed for
access-intensive
applications. Since no manufacturer committed
to develop a first-generation Accelis-based
product,
however, second-generation licenses were
not released, essentially shelving the Accelis
specification.
In contrast, the Ultrium specification was
pursued by each of the three vendors, all
of which currently offer
drives based on first-generation specification.
First-generation LTO Ultrium drives support
a native
capacity of 100GB (200GB compressed with
a 2:1 data compression ratio) and native
sustained transfer
rates up to 20 MB/sec (40 MB/sec compressed).
Ultrium uses half-inch-wide, Metal Particle
(MP) tape, a
multichannel and bidirectional format using
a linear serpentine recording method, and
Magneto-Resistive
(MR) head and servo technology. Other features
common to all first-generation LTO Ultrium
drives are:
o
Recording Format-LTO Ultrium tapes have
384 tracks recorded in four bands (96 tracks
each)
across the half-inch tape. Five servo tracks
are prerecorded onto the media to act as
guides for the
heads during reading and writing functions.
In addition, the LTO media has horizontal
servo tracks
that travel down the length of the tape
to maintain and control the positioning
of the read/write heads
on the data track. First-generation Ultrium
tape drives feature eight read/write channels.
o
LTO Cartridge Memory (LTO-CM)-All Ultrium
tape drives come with LTO Cartridge Memory
(LTO-
CM), a radio frequency (RF)-based feature
that allows certain kinds of data to be
stored on a chip
rather than in the first region of the tape.
As a result, the information is accessible
as soon as the
cartridge is loaded into the drive rather
than when the tape is actually threaded
past the head and
read. The types of data that can be stored
in LTO-CM include information on the tape
contents (such
as file location data), information from
the tape manufacturer (such as serial number,
manufacturer ID
number and maximum tape speed) and information
from the tape drive manufacturer (such as
predictive failure analysis data and information
on drive/media health). In all cases, the
chip is located
in the rear of the Ultrium data or cleaning
cartridge where it can be easily read through
an RF
interface by either a stand-alone drive
or a reader located on the robotics of a
tape library. Data in the
LTO-CM is protected with parity and CRC.
o
Interchangeability of Media-Because of the
open specification, all Ultrium drives support
any
Ultrium-certified media cartridge regardless
of manufacturer. In April 2002, the three
LTO technology
provider companies (HP, IBM and Seagate)
announced that a "universal" cleaning
cartridge for
Generation 1 LTO drives is now available
from various suppliers allowing end-users
to purchase a
single cleaning cartridge for use with all
Generation 1 Ultrium drives regardless of
the manufacturer.
The LTO Ultrium format was developed from
scratch, with no requirements for backward
compatibility.
But while the specification was designed
to ensure interoperability, it did not mandate
such things as drive
form factor, drive interface, power consumption,
reliability standards or specific tape path
designs. Each
drive/media manufacturer was therefore able
to determine how to meet the specification
requirements on
its own, thus allowing for design ingenuity
and competitive differentiation.
In April 2002, licenses for the second-generation
Ultrium format were made available. This
initiates the
product development cycle for next-generation
Ultrium drives which will support a native
capacity up to
200GB using a new second-generation data
cartridge. Performance will also improve
with native data
transfer rates up to 40 MB/sec. The Generation
2 Ultrium specification also calls for an
increase in the
number of tracks, a faster average tape
speed, and a more efficient recording method.
Ultrium Generation
2 drives will be able to read from and write
to a Generation 1 cartridge in Generation
1 format, as well as
Generation 2 cartridges in Generation 2
format. Availability of the second-generation
Ultrium drives from
all vendors is expected in early 2003.
The LTO consortium's roadmap includes four
generations of Ultrium products that double
in both capacity
and data transfer rate with each successive
generation. By the fourth generation, Ultrium
products are
expected to offer 800GB of native formatted
storage capacity and a 160 MB/sec native
data transfer rate.
For more information on LTO Technology,
see LTO Tape Technology Overview.
Half
Inch Cartridge
IBM 3480/3490/3490E
IBM is responsible for several of the half-inch
tape technologies that have developed into
de-facto
standards within enterprise data centers.
Introduced as a successor to 9-track, IBM's
3480 tape drive
revolutionized data center storage in its
time with its use of half-inch media contained
within a four-inch
square cartridge. The change from first
generation tape reels to tape cartridges
was the enabling
technology that set the stage for the development
of automated backup devices such as autoloaders
and
libraries. The 3480 was the drive used in
the early development of tape automation
robotics and its form
factor remains the standard for high-end
enterprise storage today.
The first 3480 tape drive was introduced
in 1984 with a storage capacity of 200MB
using 18-track
recording and a 3 MB/sec data transfer rate.
Five years later, IBM introduced the 3490
tape drive adding
IDRC hardware compression, which increased
storage capacity to 1GB depending on data.
The final
generation of 3480 technology, the 3490E,
increased the number of recording tracks
to 36 and added a
double length tape. The 3490E supports a
standard length cartridge with a capacity
of 400MB (1.2GB
compressed) and an extended length cartridge
with a native capacity of 800MB (2.4GB using
data
compression). The 3490E supports a channel
data rate of 9 MB/sec. The 3480, 3490 and
3490E all use
the same physical size cartridge and are
backward compatible.
IBM 3590B/3590E/3590H
IBM introduced its first generation 3590
tape technology in 1995 in conjunction with
media supplier 3M.
The 3590 leveraged many of the 3490E mechanical
components while adding the latest advances
in
recording technology. The 3590 established
a basis for a new extendable tape drive
family for use in a
broad range of computing environments.
The latest 3590 drive, the 3590 Model H,
was introduced in July 2002 with increases
in both capacity and
reliability. The Model H uses a 384-track
magnetic recording head versus 256 tracks
on the Model E and
128 tracks on the Model B. The 3590 Model
E drive can read both 128 and 256 tracks
and write 256
tracks to existing cartridges, while the
new Model H drive can read both 128 and
256 tracks and write 384
tracks to existing cartridges. The 3590
tape drive uses a bidirectional longitudinal
serpentine recording
technique as well as a magneto-resistive
head that reads and writes 16 data tracks
concurrently.
Using a standard length tape cartridge,
the 3590 Model H has a native capacity of
30GB. On the Model E,
it is 20GB and on the Model B it is 10GB.
With an extended length cartridge, native
capacity doubles to
60GB on the Model H, 40GB on the Model E,
and 20GB on the Model B tape drives. The
3590 uses the
IBM LZ1 compression algorithm, which is
based on the Lempel-Ziv algorithm and Jackson's
class of
encoding methods. The Lempel-Ziv (LZ1) data
compression technique provides a compressed
capacity
up to 90GB on Model H tape drives, 60GB
on Model E tape drives, and 30GB on Model
B tape drives
using a standard length tape cartridge (assumes
3:1 compression and compressible data).
With an
extended length cartridge, compressed capacity
goes up to 180GB on the Model H, 120GB on
the Model
E and 60GB on the Model B drives.
The 3590 Models E and H provide a native
data transfer rate of up to 14 MB/sec. With
Ultra SCSI
attachment, 3590 Models E and H are capable
of a maximum instantaneous data rate of
40 MB/sec or
sustained data rates of up to 34 MB/sec
(assumes 3:1 compression). With native Fibre
Channel
attachment, the maximum instantaneous data
rate of Models E and H is 100 MB/sec, with
sustained data
rates of up to 42 MB/sec (again assuming
3:1 compression). The 3590 Model B supports
a 9 MB/sec
native data transfer rate with a sustained
data rate of 34 MB/sec in an Ultra SCSI
environment. The Model
B drive does not support a Fibre Channel
attachment. All 3590 models support ESCON
and FICON
attachment using the 3590 A60 Controller,
which enables the drives to be shared between
ESCON and
FICON servers. Maximum FICON channel link
speed is 100 MB/sec full duplex versus ESCON
performance of 17 MB/sec simplex.
The 3590's Metal Particle (MP) tape media
is housed in a cartridge that is physically
the same size and
shape as the 3480 cartridge design. They
are, however, not compatible in any way.
They can be used in
the same automation systems (they are physically
compatible in terms of robotics handling),
but that is all.
The 3590 cartridge case has been designed
so that it can be easily detected by a 3590
drive, but a 3590
drive will reject a 3480, 3490, or 3490E
cartridge since they do not have the physical
characteristics that
are unique to a 3590 cartridge. The leader
block of the 3590 cartridge has also been
modified so that any
attempt to mount the cartridge in a 3480,
3490 or 3490E drive will be rejected.
A new MP medium with a much higher coercivity
is used in the 3590 cartridge. This is required
to support
a high aerial density, and the ability to
write a large number of tracks. The 3590
was designed for
increased data integrity and uses Error
Correction Code (ECC) and servo tracks that
are prerecorded at
the time of manufacture for precise head
positioning. These tracks enable the 3590
tape drive to position
the read/write head accurately with respect
to the media while the tape is in motion.
Additional reliability
features include resident diagnostics that
dynamically monitor drive and media performance
to detect
potential problems and preemptively aid
in resolution. The 3590 also provides redundant
data protection
capabilities. By systematically disbursing
data across the media as it is written with
redundant parity
checking bits, there is a reduced chance
of information loss should a media error
occur.
StorageTek
9840/T9840B/T9940
The StorageTek 9840 is a high-performance
tape drive with relatively low storage capacity,
targeted at
applications that require extremely fast
data access and "disklike," random-retrieval
operations. With the
9840, StorageTek introduced a new class
of data center drives capable of spanning
multiple
environments, ranging from MVS and OS/400
to Unix and Windows NT/Windows 2000. The
9840
cartridge matches the 3480 form factor and
can be mixed and matched with 3480 class
drives in the
same StorageTek tape library.
StorageTek embarked on the original 9840
design in order to accomplish new levels
of performance that
were not available in half-inch tape technology
at the time. Fundamental to the 9840's performance
is its
use of a dual-reel cartridge and self-contained
tape path, all incorporated within a 3480/3490-shaped
cartridge. By encasing the critical tape
guidance, movement and head/tape interface
mechanisms within
the cartridge, the 9840 eliminates the need
to thread up the tape within the transport.
The drive is ready
for operation as soon as the cartridge is
loaded into the transport and locked into
position. The 9840
cartridge design also leads to improved
reliability, since the tape never leaves
the cartridge enclosure,
reducing problems that may result from head/media
misalignment. The 9840 automatically loads
at the
midpoint of the tape, essentially halving
the search time to the end of tape and resulting
in superb data
access speeds during restore operations.
Before unloading, the 9840 repositions the
tape to its midpoint
location for future use.
In October 2001, StorageTek introduced a
new second-generation 9840 drive called
the T9840B. The
T9840B boosts performance over the first-generation
9840, but with no increase in capacity.
Both T9840B
and 9840 have a native storage capacity
of 20GB, and their use of enhanced LZ-1
data compression
technology allows compressed capacities
of typically 80GB using a 4:1 compression
ratio in MVS/ESCON
mainframe environments. In open-system environments
running Unix or Windows NT/2000 on SCSI
or
fiber, 2:1 compression ratio is common,
providing capacities up to 40GB. The T9840B
supports a native
data transfer rate of 19 MB/sec, nearly
two times the original 9840's 10 MB/sec
native data transfer rate.
This is primarily the result of a doubling
of tape speed during read/write operations
from 79 inches/second
on the 9840 to 158 inches/second on the
T9840B. Tape speed during rewind and search
operations
remains the same for both drives at 315
inches/second. The size of the T9840B's
data buffer has been
increased to 32MB from 8MB on the 9840,
further improving drive performance. The
maximum internal
data transfer rate of the T9840B has been
increased to 70 MB/sec from the 9840's maximum
internal
throughput of 40 MB/sec, both assuming highly
compressible data. This allows the fibre
channel version
of the T9840B drive to more fully exploit
mainstream 100 MB/sec fibre channel connections.
The T9840B
has also been designed with a 2-Gigabit
fibre channel controller interface protecting
a customer's
investment by providing a growth path into
200 MB/sec fibre channel storage area network
(SAN)
infrastructures. With 2:1 compression, the
T9840B can therefore achieve data transfer
rates approaching
40 MB/sec using an Ultra SCSI interface
in an open systems environment.
The T9940 is StorageTek's "capacity-centric"
solution, geared toward environments that
require the same
robustness as the T9840B and 9840, but where
the customer is willing to trade off data
access time to get
greater storage capacity. StorageTek's T9940
tape drive is based on first-generation
9840 technology and
shares many components with the 9840 drive;
however, it delivers a higher storage capacity
in exchange
for slower search and data access times.
The T9940 supports a native capacity of
60GB and, like its high-
performance counterpart, uses enhanced LZ-1
compression techniques that typically provide
120GB of
compressible data in Unix and Windows NT/2000
operating environments and 240GB in MVS
mainframe
environments. The T9940's higher data capacity
is achieved by using a single-reel tape
cartridge that
holds more tape than the 9840's dual-reel
cartridge. Search time and first access
to data averages 41
seconds, or approximately five times that
of the 9840 tape drive. The T9940's average
file access time in
subsequent searches is 30 seconds, assuming
a search of 1/3 the tape length. Tape load
and initialize
time is 18 seconds, compared with the 9840's
four seconds, and its maximum rewind time
is 90 seconds,
compared with the 9840's 16 seconds. Connectivity
options for the T9940 support both mainframe
and
open systems environments using ESCON, Ultra
SCSI and fibre-channel interfaces. All other
T9940
specifications are identical with the original
9840.
Helical-Scan
Technologies
Hewlett-Packard, Sony and Exabyte pioneered
the use of helical-scan technology for data
backup
applications. By leveraging the mechanisms
used in video and audio recorders, the intent
was to
capitalize on economies of scale, thus reducing
cost and time to market.
Helical-scan tape drives record data on
tracks that are written at an angle on the
tape rather than parallel
with the tape edge as with linear recording.
The read/write heads in helical scan tape
drives are mounted
on a spinning drum, which is known as a
rotary head. The head is oriented at a slight
angle relative to the
tape and contains two read heads and two
write heads alternately spaced 90 degrees
apart. The tape
moves in the opposite direction to the rotary
head, and multiple tracks are recorded and
verified
concurrently. Typically, the tape supply
and take-up reels are both contained within
the cartridge. In most
of these drives, the tape is pulled into
the drive and then wrapped partially around
the drum. The tape
path is part of the device. Helical-scan
tape drives fall into the following categories
based on the type of
media or cartridge and the width of the
tape.
4-mm
Helical Scan Digital Audio Tape/Digital
Data Storage (DAT/DDS)
Digital Audio Tape (DAT) was originally
developed as a format for consumer audio
applications and was
later expanded by Hewlett-Packard and Sony
through the Digital Data Storage (DDS) standard
so that
DAT drives could be used for reliably storing
computer data. Specifications for the current
DAT standard,
DDS-4, were developed in 1997 and endorsed
by the Digital Data Storage Manufacturers
Group, which
consists of industry-leading tape storage
organizations.
DDS-4 has a native capacity of 20GB on a
single data cartridge (40GB compressed with
a 2:1 data
compression ratio) at native backup speeds
up to 2.75 MB/sec (5.5 MB/sec compressed).
Compared to
the previous DDS-3 DAT standard, that represents
a 67 percent increase in capacity and a
150 percent
increase in performance. The increased capacity
of DDS-4 is accomplished through a reduction
in the
track pitch from 9.1 µm to 6.8 µm,
increasing the number of tracks written
over 1 mm of tape from 12
tracks to 16. DDS-4 also uses an increased
tape length of 155 meters (up from 125 meters).
The
increased transfer rate is achieved by improvements
in read/write head technology, increased
drum
speed, improved channel recording techniques
and advances in media technology.
Sony and HP both stated that they would
undertake no further development of the
10-year-old DDS
standard beyond the DDS-4 format. Sony will
instead replace its DDS line with AIT solutions
starting with
the enhanced AIT-1 drive, while HP will
cover the space that it traditionally sold
DDS with DLT1 products.
Exabyte has also entered the segment and
is attempting to lure DDS users with its
VXA products that
were acquired in late 2001 through its merger
with Ecrix Corporation.
8-mm
Helical Scan
Early adaptations of 8-mm tape drives were
based on video camcorder technology with
modifications for
storing computer data. Today's secondary
storage manufacturers now design this class
of product
specifically for computer data storage applications.
All products in this category record data
on 8-mm-wide
media.
There are two main 8-mm-based protocols
that encompass all ongoing product development
using this
platform. Exabyte was the driving force
behind the use of standard 8-mm technology
and has evolved the
technology through its proprietary Mammoth
and Mammoth-2 developments. Sony and Seagate
have
developed the Advanced Intelligent Tape
(AIT), which has since evolved into the
second-generation AIT-2
format and the third-generation AIT-3 format.
Although Mammoth and AIT are both 8-mm technologies,
the two formats are incompatible and cannot
share media interchangeably.
Mammoth
Technology
Although based on 8-mm helical-scan recording
technology, the first-generation MammothTape
drives
(Mammoth-LT and Mammoth) incorporated several
significant improvements over the original
8-mm
drives that used camcorder-based mechanisms.
With Mammoth, an Exabyte-designed and manufactured
industrial-quality deck design was introduced
that eliminated the capstan and pinch-roller
system. The
capstanless design removed the part of the
drive that places the most pressure on the
tape media,
causing unpredictable wear and reducing
reliability. A larger scanner was added
that completely records
the tape from edge to edge, providing higher
capacity and data transfer rates. With the
introduction of
Mammoth, Exabyte also added an improved
tape transport system that supports Advanced
Metal
Evaporated (AME) media-an alternative that
is cleaner to use and provides greater capacity
than Metal
Particle (MP) tape. In addition, Exabyte
changed the tape path design to reduce potential
stress points on
the tape. Finally, with Mammoth technology
came an innovative approach to extending
cleaning intervals
through the use of a cleaning wheel called
a Dynamic Head Cleaner that reduces the
likelihood of head
contamination by briefly touching the scanner
and heads whenever a tape is loaded. The
Dynamic Head
Cleaner also automatically performs a cleaning
after each 80 minutes of continuous tape
motion and can
be invoked by the drive's firmware if needed
during extended backups.
The second-generation MammothTape drive,
Mammoth-2 (M2), has a native formatted capacity
of 60GB
(150GB with a 2.5:1 data compression ratio)
and a native sustained data transfer rate
of 12 MB/sec (30
MB/sec compressed). It includes a 32MB adaptive
buffer that works to compensate for any
inconsistencies in data flow from the host.
It also uses an enhanced Partial Response
Maximum
Likelihood (PRML) data-encoding scheme and
Adaptive Lossless Data Compression (ALDC)
as its
compression engine, yielding a compression
ratio of 2.5:1 for higher capacity. The
M2 features a four-
channel/eight-head scanner in contrast to
the Mammoth-1 drive, which had a two-channel/four-head
scanner. The additional read/write heads
quadruple the tape drive's transfer rate.
The M2 also adds improvements in the area
of tape reliability by using a unique three-pronged
approach
to keeping the drive clean. First, it features
a Dynamic Head Cleaner, the small cloth-covered
wheel
described above. Second, the M2 uses a set
of inactive burnishing heads to prep the
tape before it
reaches the active read/write heads. These
"conditioning heads" are intended
to make sure that the tape
is set at the correct air bearing and to
remove any contaminants from the tape's
surface before it passes
over the read/write heads. Third, the M2
utilizes special AME media, which is equipped
with Exabyte's
proprietary "SmartClean" technology.
This media design includes a section of
cleaning material at the
beginning of each recording tape so that
the drive can automatically clean itself
when necessary.
The M2 was the first helical-scan drive
to offer support for native fibre channel
connectivity by attaching
directly to the SAN, eliminating the need
for fibre channel-to-SCSI routers. M2's
one-Gigabit fibre channel
interface allows throughput of up to 100
MB/sec per path. Along with lowered infrastructure
costs, this
type of interface allows the M2 to support
serverless backup with the extended copy
command that is
embedded into M2 firmware, making continuous,
7x24 backup possible. E-copy is Exabyte's
implementation of the SCSI Extended Copy
command within the M2 drive and allows the
direct transfer of
data between disk and tape. Data can be
transferred across the SAN without the intervention
of a server,
eliminating a potential bottleneck in the
backup process.
Exabyte announced a new market strategy
in April 2002 that redirects the development
of its third-
generation MammothTape drive, the Mammoth-3
(M3), which was underway. Now that Exabyte
has fully
integrated Ecrix Corporation into its operations,
the company will attempt to capitalize on
its acquired VXA
technology by integrating it with MammothTape
and deliver a new set of products that will
provide
improved price/performance and reliability.
The new Mammoth-3 will offer a compressed
capacity of
625GB and a compressed transfer rate of
60 MB/sec. The drive will be available in
two versions, one that
will be backward-read compatible with VXA
products, and another with additional backward-read
compatibility with M2.
VXA
Technology
VXA tape technology was created by Ecrix
Corporation, which entered into a merger
agreement with
Exabyte in August 2001. As of November 2001,
Ecrix's operations were fully integrated
with Exabyte and
now operate under the Exabyte name.
Exabyte will continue to focus its VXA technology
on the low-cost market segment. The next-generation
VXA-2 became available in June 2002. The
VXA-2 drive offers a compressed capacity
of 160GB and a
compressed data transfer rate of 12 MB/sec.
VXA-2 pricing is expected to be comparable
to the VXA-1 at
introduction. The VXA roadmap includes at
least two more product generations following
VXA-2. The
VXA-3 is projected to support 320GB of compressed
capacity at a 16 MB/sec compressed data
transfer
rate, while VXA-4 is expected to offer 640GB
of compressed capacity at speeds up to 32
MB/sec
compressed.
VXA offers a unique approach to data recording
that allows it to address some of the inherent
weaknesses associated with streaming tape
technologies. In order for a linear or helical
tape drive to
operate at peak efficiency, large blocks
of data must be read or written from the
drive while the tape is
moving at a constant speed (or "streaming")
to keep the drive's data buffer full. When
"streaming" is
interrupted, the drive must reverse direction
and reposition the tape before read/write
operations can
resume.
VXA uses a proprietary data format and algorithms
for data verification and correction. Instead
of
formatting data on a tape in long strings,
which requires the drive to stream for optimum
read/write
performance, VXA breaks the long data strings
into smaller packets before being recorded
on the media.
VXA's Discrete Packet Format (DPF) uses
64 bytes of user data per packet and 387
packets per track.
Data packets also contain a synchronization
marker, unique address information, Cyclic
Redundancy
Check (CRC) code and Error Correction Code
(ECC).
During a read operation, the VXA drive uses
all four leading and trailing heads to scan
the tape and read
the data packets into a buffer segment.
The packets that compose a data string may
arrive at different
times in the data buffer. Because each packet
has a unique address, the VXA buffer architecture
efficiently reassembles the packets in the
correct order, regardless of the order in
which they were
received. The VXA data buffer retrieves
data with each pass of the read heads until
all data packets are
loaded into the buffer.
Much like other streaming tape technologies,
VXA does not rely on precise alignment of
heads and data
tracks to read or write data reliably. Instead,
VXA reads and writes data in packet form
and overscans the
recorded area of the tape. Overscanning
requires a system architecture that eliminates
the dependency
on the alignment geometry between the tape
path and the recording head. To read or
write data,
streaming tape devices depend on a constant
head-to-tape speed for linear recording
or a constant track
angle for helical-scan recording. VXA's
technique allows each channel of the drive
to scan an area
greater than 100 percent of the recorded
area of the tape, ensuring a full data recovery
and increasing the
reliability of data interchangeability between
different VXA drives.
VXA's Variable Speed Operation enables it
to continually adjust the tape speed to
match the actual data
transfer rate between the drive and the
host. Because VXA can vary the speed at
which it sends or
receives data, it is unlikely that VXA ever
has to stop the motion of the tape completely.
In the rare
instance that data transfer operations do
stop, the VXA drive can gently slow down
to a "Ready Mode"
and then restart from that location when
read/write operations resume. By eliminating
tape repositioning,
VXA reduces performance degradation as well
as wear on the media and drive mechanism,
which can
compromise the reliability of the data.
The combination of VXA's Discrete Packet
Format, its ability to alter the speed of
the tape to match
available host bandwidth and an overscanning
technique which allows data to be read from
any physical
location on the tape without having to follow
a chain of tracks from beginning to end
results in a new and
economical backup technology which is fast,
reliable and less sensitive to media errors.
Advanced
Intelligent Tape (AIT) Technology
Sony produced the first AIT tape drive in
1996 with the goal of doubling capacity
and transfer rate every
two years. AIT falls into the 8-mm category,
and its cartridge is the same size as other
8-mm tape
cartridges, but its recording method is
proprietary and incompatible with 8-mm products
from Exabyte. AIT
drives include a cartridge-sensing system
to ensure that only cartridges designed
for AIT drives are used.
AIT AME media contains a special ID that
the drive will recognize. If an AIT AME
cartridge is mistakenly
inserted into a non-AIT 8mm drive, a write-protect
feature will be activated to protect it
from possible data
corruption.
The first-generation AIT format, the AIT-1,
supported a native capacity of 25GB (65GB
compressed with a
2.6:1 data compression ratio) and a 3 MB/sec
native sustained transfer rate (7.8 MB/sec
compressed). An
extended-length tape for the AIT-1 drive
was later added to increase the maximum
native capacity to
35GB (91GB compressed). An AIT-1 enhancement,
dubbed the "Valueline" AIT-1,
was introduced in
January 2001 and leverages elements of the
AIT-2 design to increase the AIT-1 drive's
native data
transfer rate to 4 MB/sec (10.4 MB/sec compressed).
The Valueline AIT-1 also added an Ultra
Wide SCSI
interface, a 10MB data buffer and increased
the rotational speed of the drum to 6,400
RPM. It uses a
Partial Response Maximum Likelihood (PRML)
data-encoding scheme to support its high
linear recording
density of 116,000 bits per inch (bpi).
The high compression rate is achieved using
a customized and
optimized version of IBM's Adaptive Lossless
Data Compression technology (ALDC), which
delivers a
2.6:1 data compression ratio, although actual
compression efficiency largely depends on
data type.
AIT-1 uses a unique head geometry and tension
control system which helps to reduce tape
tension by as
much as 50 percent when compared with competing
technologies. Tape tension is a critical
factor in head
and media wear, and AIT's extremely low
and carefully controlled tape tension results
in a 50,000-hour
head life. Its Auto Tracking Following (ATF)
servo system senses and corrects any off-track
positioning,
keeping the tape perfectly centered on the
read/write head for data accuracy.
Introduced in March 1999, the second-generation
AIT drive, AIT-2, provides full backward
compatibility
with AIT-1 while doubling the native capacity
of the original AIT-1 drive to 50GB (130GB
compressed).
The native data transfer rate was likewise
doubled to 6 MB/sec (15.6 MB/sec compressed).
This doubling
of capacity and speed was accomplished through
technological advances in both the drive
(recording
heads, channel coding, media formulation
and mechanism design) and recording media.
AIT-2 also has a
10MB data buffer and uses a Trellis-Coded
Partial Response (TCPR) encoding method,
which increases
its linear recording density to 167,000
bits per inch. The rotational speed of the
AIT-2 drum was increased
from 4,800 RPM to 6,400 RPM. AIT-2 uses
Sony's patented HyperMetal laminate heads
and an on-drum
amplifier to enhance the signal to the head
and reduce noise, thereby minimizing read
errors.
AIT drives use an Advanced Metal Evaporated
(AME) tape media, which reduces the accumulation
of
deposits on the head. AME media is made
without nonmagnetic binder materials that
can contaminate the
read/write heads or produce other media-related
drive errors. AME's Diamond-Like Carbon
(DLC)
abrasive resistant coating limits wear on
the head and media and eliminates the need
for cleaning tapes.
The head itself detects any accumulation
of deposits on the head from changes in
error rates. When the
head detects deposits, it automatically
initiates a self-cleaning process using
the built-in head cleaner,
thus eliminating the need to clean the head
regularly using a cleaning cartridge.
AIT's key differentiating feature is intelligence
embedded into the tape cartridge called
Memory-In-
Cassette (MIC). Sony's MIC technology was
introduced with the first-generation AIT-1
drive and later
enhanced in the AIT-1 extended-length tape
model and on AIT-2. MIC is a 64Kb flash
memory chip (16Kb
on SDX1-25C tape media) that is incorporated
into the data cartridge and stores various
system and user
information directly within the MIC structure
to enhance data reliability, error prediction
and access
performance. On-chip data includes system
logs, search map and user-definable information,
allowing
fast access to data anywhere on the tape.
Storing key data parameters in nonvolatile
memory that is an
integral part of the cartridge rather than
on the tape media provides fast access to
on-tape structures and
media statistics by any MIC-compatible AIT
drive without having to first read the physical
tape media. The
MIC detects ID data for the requested information
and moves the tape at its rewind speed (122
inches/second on AIT-1 and 160 inches/second
on AIT-2) to the approximate location of
the data. Then it
slows down to read the ID blocks on the
tape to locate the specific data requested.
AIT supports an
average data access time of 27 seconds (using
a 170m tape), which is more than 2x improvement
when
compared with competing technologies. Other
tape technologies maintain directory information
in a
header area on the tape media itself that
must be read each time a tape is loaded
and rewritten when any
modifications to data are made. The MIC
also supports multiple partitions and load
points, which allows
the loading and unloading of a cartridge
to occur without having to rewind the tape
to the beginning. The
ability to park the tape at any one of the
64 on-tape partitions means that an AIT
drive can support a
"midpoint load" (similar to the
StorageTek 9840), which would essentially
halve the search time to the end
of tape in either direction, resulting in
fast data access speeds during restore operations.
This assumes
that before unloading a cartridge from the
drive, the tape was positioned to its midpoint
location for future
use.
Sony's third-generation AIT product, the
AIT-3, was made available for sale in November
2001. The AIT-3
doubles the capacity and performance of
AIT-2 and is fully backward read and write
compatible with all
AIT-2 and AIT-1 media, enabling users to
seamlessly migrate to the higher capacity
of AIT-3 without
losing access to previously backed-up data.
A new 230-meter data cartridge, the SDX3-100C,
has been
designed for use with the AIT-3. AIT-3 supports
a native capacity of 100GB (260GB with 2.6:1
data
compression) and a native data transfer
rate of 12 MB/sec (31.2 MB/sec compressed).
The increased
capacity of AIT-3 was achieved by narrowing
the track pitch from 11 microns on AIT-1
and AIT-2 to 5.5
microns on AIT-3. The increase in data transfer
rate results from a number of factors, including
doubling
the number of channels (from two to four),
doubling the number of heads (from four
to eight),
simultaneously utilizing two recording heads
on tape, and the increased area density.
The data buffer has
also been increased from 10MB on AIT-1 and
AIT-2 to 18MB on AIT-3.
Like the AIT-1 and AIT-2, the AIT-3 is designed
in a 3.5-inch form factor. AIT-3 supports
an Ultra 160
Wide SCSI LVD/SE interface, allowing it
to support up to a 160 MB/sec synchronous
burst data transfer
rate, whereas AIT-1 and AIT-2 both use an
Ultra Wide SCSI LVD/SE interface with a
maximum
synchronous burst data transfer rate of
40 MB/sec. AIT-3 drives incorporate Sony's
new Remote-Memory-
In-Cassette (R-MIC) media interface system.
The R-MIC enables the drive to access key
tape parameters
embedded in the data cartridge without the
tape being loaded, improving access time
to data. This is a
particularly useful feature for tape automation
applications.
Sony continues to maintain its commitment
to the AIT roadmap and its design goal of
doubling both
capacity and performance every two years
for six generations. In doing so, it has
provided general
visibility for AIT-4, AIT-5 and AIT-6 capacity
and performance, which is in keeping with
its design goal.
S-AIT
In November 2001, Sony made a technology
announcement indicating its plans to develop
a next-
generation AIT format called S-AIT. Like
AIT, S-AIT is based on helical scan recording
technology. The
new specification will allow for native
capacities up to 500GB on a single cartridge,
with native data
transfer rates up to 30 MB/sec. With 2.6:1
compression, the first-generation S-AIT
drive will be capable of
storing up to 1.3TB of data on a single
cartridge at transfer rates up to 78 MB/sec.
Like it did with AIT,
Sony has stated its goal of doubling capacity
and performance every two years, allowing
the S-AIT
architecture to reach native capacities
of 4TB and native transfer rates of 240
MB/sec. S-AIT drives will be
housed in a full height 5.25-inch extended
drive form factor, whereas existing AIT
models use a 3.5-inch
form factor. First-generation S-AIT drives
are expected to support Ultra 160 SCSI and
fibre channel
interfaces. S-AIT is expected to leverage
some of Sony's technology and component
research done for
AIT, but will use a 600m single-reel, half-inch
tape cartridge housed in a cartridge similar
to an LTO or
SDLT cartridge. The form factor of S-AIT
drives and its media should allow for quick
integration into
existing automation solutions. S-AIT media
will include R-MIC technology, which enables
fast load times
and data searches. Sony has partnered with
Matsushita, a company with expertise in
helical-scan product
design and manufacturing, to bring S-AIT
to market in the late 2002 or early 2003
time frame.
Tape
Automation Products
As data storage capacity requirements increase,
the need for higher-capacity tape storage
solutions
grows. One way to gain additional capacity
and simplify the backup and retrieval process
at the same
time is through automation. In fact, today's
tape drives are frequently designed with
the automation
market in mind, with drive manufacturers
working closely with automation vendors
to ensure compatibility
before the new drives are even released.
There are two types of automation products
for users who need more storage capacity
than a single tape
can hold-autoloaders and tape libraries.
Autoloaders are single-drive mechanisms
that exist in an
enclosure that features a multiple-cartridge
magazine and a robotic system to insert
and remove the
cartridges from the drive automatically.
Tape libraries go a step further with multiple
drives and many
more cartridges for even greater storage
and faster archival and retrieval.
Technology
Analysis
In an industry where the time between a
product's launch and its obsolescence can
sometimes be
counted in mere months, it is extraordinary
that tape drive technology remains such
a predominant
component of the storage mix. Tape has been
the technology of choice for data backup
since the advent
of computing, and continued breakthroughs
in drive, media and automation robotics
design should help it
maintain its leadership position.
The key to the survival of tape technology
may well be the manufacturers' willingness
to adapt and evolve
the technologies to the changing needs of
the market. Customers expect tape technology
providers to
deliver improved capacity and performance
on an ongoing basis and at roughly the same
cost per
megabyte. Depending on the scalability of
the technology, manufacturers may modify
a particular design
to deliver improvements in data transfer
rates, capacity and reliability. In other
instances, a complete new
architecture is required to make the improvements
necessary to remain competitive. Exabyte
went
through this transition when it moved from
its original 8-mm tape drive technology
to its first-generation
Mammoth technology and then again as it
transitioned to its second-generation Mammoth-2.
Likewise,
IBM, Hewlett-Packard and Seagate, through
their cooperative design effort, have all
gone through a
similar process, resulting in the development
and introduction of LTO Ultrium-based products.
Quantum
progressed from its DLTtape technology to
SDLTtape, which, although it is positioned
as the follow-on
product to DLTtape, incorporates a significant
number of new technologies as well.
Although the customer's alignment around
one camp or the other (linear or helical
technologies) has
historically been at the center of the decision
criteria, both technologies have evolved
over the years, and
many of the negative factors of each one
have been addressed.
Business
Use
Demand for tape and tape automation products
continues to expand in spite of predictions
that it is a
technology on the decline. Tape technologies
continue to evolve in an effort to meet
customer demands
for performance, capacity, scalability and
reliability in storage solutions.
As businesses commit more and more of the
time that used to be available for backup
tasks to around-
the-clock operations, backup windows are
rapidly shrinking, and the cost of downtime
has increased
significantly. With the advent of such storage
management applications as remote copy and
snapshot
copy, users now have the ability to make
a rapid copy of their data and then utilize
tape technology to
back up the data faster than ever. While
there is the threat of optical technologies
on the horizon, for the
time being tape technologies are holding
their own. In 2001, the total industry expenditure
for tape drives
of all formats (factory revenue based on
worldwide shipments) was approximately US$2.62
billion,
according to Gartner Dataquest figures.
That was down from US$3.01 billion in 2000.
Technology Leaders
Leaders in the tape storage market include
Benchmark Tape Systems, Exabyte, Hewlett-Packard,
IBM,
OnStream Data B.V., Quantum, Seagate Removable
Storage Solutions, Sony Electronics, Storage
Technology and Tandberg Data.
Benchmark Tape Systems Corporation (Boulder,
Colorado)
Founded in May 1998, Benchmark Tape Systems
Corporation develops tape and storage solutions
that
are based on standard DLTtape technology
licensed from Quantum Corp., a minority
investor. In 2001,
Benchmark achieved a 4.6 percent unit market
share (3.1 percent based on factory revenue)
of the "small
form factor half-inch cartridge/other data
cartridge" market segment, according
to Gartner Dataquest.
Exabyte Corporation (Boulder, Colorado)
Exabyte was one of the pioneers in 8-mm
data storage technology and created both
the Mammoth and
the M2 standards as a means of moving the
technology into midrange markets. Exabyte
also offers a line
of tape automation solutions based on MammothTape,
VXA, AIT-2, DLTtape and LTO Ultrium
technologies. In November 2001, Exabyte
and Ecrix Corporation completed a merging
of operations
operating as a single entity under the name
Exabyte. Ecrix pioneered the development
of VXA tape
technology, which offers an innovative approach
to improving data reliability across all
price points.
Hewlett-Packard Corporation (Cupertino,
California)
Hewlett-Packard's tape products compete
in three market segments-minicartridge,
4-mm helical scan,
and "small form factor half-inch cartridge/other
data cartridge" (with its two LTO Ultrium
drives). In 2001
the company achieved unit market shares
of 3.9 percent for minicartridge, 44.4 percent
for 4-mm helical
scan, and 8.4 percent for "small form
factor half-inch cartridge/other data cartridge"
and factory revenue
market shares of 4.6 percent for minicartridge,
54.2 percent for 4-mm helical scan, and
14.2 percent for
"small form factor half-inch cartridge/other
data cartridge," according to figures
from Gartner Dataquest.
HP was one of three members of the open
architecture LTO consortium that developed
the two LTO
specifications, demonstrating its commitment
to tape technology by dedicating vast R&D
resources to the
new format's development.
IBM
(Armonk, New York)
IBM offers products in both the high-end
and the low-cost half-inch cartridge market
segments, as well as
in the "small form factor half-inch
cartridge/other data cartridge" segment
(with its Ultrium entry). IBM was
not only one of the three founding members
of the LTO open tape architecture consortium,
it was also the
first to release a product to market based
on the Ultrium specification. According
to Dataquest, the
company had a 7.7 percent share of the small
form factor half-inch cartridge/other data
cartridge market
segment based on units shipped (17.5 percent
based on factory revenue) in 2001.
OnStream
Data B.V. (Eindhoven, the Netherlands)
OnStream Data B.V. is a new company formed
in May of 2001 through the acquisition of
intellectual
property and other assets from the former
OnStream, Inc., after they ceased operations
in March of 2001.
Philips Electronics originally developed
OnStream's ADR technology. A sister company,
OnStream MST,
manufactures the state of the art thin film
heads used in the ADR tape drives manufactured
by OnStream
Data. In 2001, OnStream Data achieved a
15.6 percent unit market share (24.7 percent
based on factory
revenue) of the minicartridge market segment,
according to Dataquest.
Quantum
Corporation (Milpitas, California)
According to Dataquest, Quantum, with its
line of DLTtape and SDLTtape products, was
responsible for
58.7 percent of the unit shipments and 54.8
percent of the factory revenue in the "small
form factor half-
inch cartridge/other data cartridge"
market segment for 2001.
Seagate
Removable Storage Solutions (Costa Mesa,
California
Like Hewlett-Packard, Seagate Removable
Storage Solutions (RSS) competes in three
different market
segments-minicartridge, 4-mm helical scan
and "small form factor half-inch cartridge/other
data
cartridge" (with its Viper 200 LTO
Ultrium drive). In 2001, the company had
a 79.9 percent unit market
share (69.8 percent factory revenue market
share) in the minicartridge market, a 29.8
percent unit market
share (24.1 percent factory revenue market
share) in the 4-mm helical-scan category
and a 2.2 percent
unit market share (2.8 percent factory revenue
market share) in the "small form factor
half-inch
cartridge/other data cartridge" segment,
according to Gartner Dataquest. Seagate
is the third member of
the LTO open tape architecture consortium
and has likewise committed enormous resources
to the
development of the new format.
Sony
Electronics, Inc. (San Jose, California)
Sony Electronics competes in both the 4-mm
helical-scan and the 8-mm helical-scan segments,
where,
according to Gartner Dataquest, it achieved
market shares of 25.1 percent and 50.4 percent,
respectively,
in 2001, based on unit shipments. Looking
at market share by factory revenue, Sony
had a 21.2 percent
share of the 4-mm helical-scan market and
a 48.2 percent share of the 8-mm helical-scan
market
segment in 2001. The company, which has
been in the tape business for over 50 years,
codeveloped the
4-mm DDS tape format and was the sole developer
of AIT technology (its 8-mm offering).
Storage
Technology Corporation (StorageTek) (Louisville,
Colorado)
StorageTek remained the market leader in
the high-end, half-inch cartridge segment,
with 55.8 percent of
the units shipped and 53 percent of the
factory revenue in 2001, according to Gartner
Dataquest figures.
In addition, StorageTek is a player in the
other helical-scan market, competing primarily
with Sony and
Ampex.
Tandberg
Data ASA (Oslo, Norway)
Tandberg Data has been the sole manufacturer
of quarter-inch data cartridge (QIC) tape
drives since
1998, with its tape drives based on SLR
technology. Tandberg Data has an exclusive
licensing agreement
with Quantum Corporation, which allows it
to compete in the "small form factor
half-inch cartridge/other
data cartridge" market segment with
a line of DLTtape and Super DLTtape drives
that it sells to
distributors and OEMs headquartered in Europe,
Asia/Pacific and Japan. The agreement calls
for
Quantum to focus its efforts on marketing
and selling DLTtape and Super DLTtape drives
in North
America and Latin America. According to
Gartner Dataquest, the company had a 1.8
percent share of the
small form factor half-inch cartridge/other
data cartridge market segment based on units
shipped (2.0
percent based on factory revenue) in 2001.
Other
Tape Drive Vendors
In addition to those named above, there
are a number of other vendors who play a
role in this market.
They include Ampex (other helical scan),
Fujitsu (low-cost and high-end, half-inch
cartridges), M4 Data
(low-cost, half-inch cartridge) MKE/Panasonic
(4mm helical scan), NEC (high-end, half-inch
cartridge),
Overland Data (low-cost, half-inch cartridge)
and Victor Data Systems (low-cost, half-inch
cartridge).
Insight
The tape market has long been characterized
by the vast proliferation of competing technologies
available
for use. Whereas users once lauded the flexibility
of choice this provided, uncertainty and
confusion grew
as the number of options increased. And
as overall data capacity needs increase
and data availability
requirements move to 7x24 continuous operation,
demands to shrink backup windows and reduce
restore
or recovery times continue to pressure tape
technology manufacturers to deliver the
innovative solutions
needed to address these requirements. Today,
vendors are working hard to develop ever-faster
and
larger-capacity drives while still paying
close attention to the issue of backward
compatibility in an effort to
retain the loyalty of their respective installed
bases.
The introduction of LTO Ultrium and Super
DLTtape opened the door for increased competition
in the
user's favor as the natural flow of competition
works to help keep costs in check. In the
helical-scan camp,
the November 2001 introduction of Sony's
AIT-3 and the expected introduction of its
new S-AIT model by
end of year 2002 continues to put pressure
on linear tape technology manufacturers
as both sides
compete for end-user as well as automation
OEM business.
As tape technology continues its evolution,
there are still a multitude of different
tape technologies to
choose from, each with its own advantages
and disadvantages in the key metric areas
of capacity,
performance, reliability and price. Customers
should continue to evaluate their options
based on their
unique storage environment, their future
growth requirements, their backward-compatibility
needs, and
the advantages and disadvantages of the
various tape technologies.
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