Super DLTtape-SDLT Technology

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

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.