StorageTek 9840, T9840B, T9940

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

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.