2. Longitudinal Recording Technology In 1984 IBM introduced the 3480 cartridge drive and format as a replacement for the ageing 3420 series of nine-track drives. For large, off-line mainframe storage, 3480 became the de-facto standard. The 3480 is a longitudinal recording device that writes 18 tracks on a 1/2" cartridge. The initial storage capacity was 200Mb per cartridge with a transfer rate of up to 3Mb per second. The table below describes the main longitudinal recording devices : Table 1 : Longitudinal Recording Technology Media Storage Capacity (GB) Transfer Rate (MB/s) Price Band (GBP) 3480 0.2 3 5-10K 3490E 0.8 3/6 5-10K DLT-2000/3000 10/15 1.25/1.5 <5K DLT-4000/7000 20/35 1.5/5 <5K DLT-8000 40 6 <5K SuperDLT 110 11 <5K Magstar MP 3570 5 2.2 5-10k Magstar 3590-B 10 9 10-20K Fujitsu M8100 10 13.5 10-20K Magstar 3590-E 20 14 20-30K IBM 3580 (Ultrium) 100 15 20-30K STK-9940 20 10 10-20K As the above table denotes, the basic 3480 cartridge has evolved. IBM's first enhancement was the addition of a compression option Improved Data Recording Capability (IDRC). The 3490E uses 36 tracks and extended length tape to increase capacity to 800 Mb. However IBM continued research and development into a device named New Tape Product (NTP). This was later to be marketed under the name of Magstar (or 3590-Tape Series). The Magstar drive was formally announced in April 1995 and became readily available in 1996. With an initial price of £35,000 (half that of other competing high capacity drives), the Magstar was popular and has been in great demand ever since. The Magstar still maintained the 3480 form factor, but now the 3590-E has a native capacity of 20GB with a data transfer rate of 14Mb per second. Magstar uses a bi-directional longitudinal serpentine recording technique, and a second generation magneto-resistive head that reads and writes 16 track groups with 8 tracks per group, providing a total of 128 tracks. Increased reliability and integrity is also offered with improved error correction code and resident diagnostics, IBM claiming up to a 100-fold increase in data integrity over 3490E. Magstar also offers a 5 metres per second search mechanism to provide rapid access to stored data. The 3590-E drive mechanism offers a superior 16MB data buffer and tape speed of 3.14 m/s. Both StorageTek (a company formed from ex-IBM Storage specialists) and Fujitsu also offer IBM-3590 compatible tape subsystems. IBM also offer an 'investment protection' scheme enabling the upgrade from 3590-B to 3590-E for £10,000. The Magstar cartridges are still of the 3480/90 form factor, hence can co-exist in a traditional 3480 automated library system with few modifications. The cartridge is loaded with 1100 feet of 1/2" wide backcoated metal particle media. A color-coded leader block has been re-designed to prevent accidental threading and running in a 3480/90 drive. The latest release from IBM - The IBM 3580 (Ultrium) is the results of the Linear Tape Open (LTO) consortium. The LTO-open programme is a joint initiative involving IBM, Hewlett Packard, Seagate Corporation and 16 other licensed leading tape and drive manufacturers. Co-opetition is encouraged - co-operatively creating a new business opportunity then competing for market share. LTO utilises multi-channel serpentine recording technology. The Ultrium specification is 384 tracks across (split into 4 bands of 96 tracks). The ½ inch LTO-Ultrium specification is 100GB native capacity at 15MB per second data transfer rate. Also of note is the DLT drive (Digital Linear Tape), another 128-track serpentine longitudinal recording device. Initially this drive was aimed at the server and enterprise backup market, offering storage capacities up to 40Gb with data transfer rates of 6 Mb per second. The price of a drive in the region of £1,500 to £4,500. The cartridges are1/2", based on Digital's CompacTape III design (similar to a TK cartridge). DLT has proved to be popular with an estimated 1 million drives in operation worldwide, and an estimated 89% of the mid-range market segment. The DLT 8000 uses DLT IV tapes and read DLT II and DLT III backward compatible The drive utilises variable speed recording technology set automatically according to the hosts bus speed. The latest release the SuperDLT drive is based on Quantum-developed Laser Guided Magnetic Recording. The SuperDLT 220 operates at a native capacity of 110GB with a transfer rate of 11MB/sec. The drive is backward-read compatible and able to read DLT-IV tapes but has no record capability on DLT-IV tapes. With SuperDLT cartridges costing in excess of £85. Table of Contents Introduction Longitudinal Recording Technology Helical Scan Technology Optical Technology Summary The Future See other technical papers.