SLR to the rescue?
The past, present and future of ADR and SLR tape formats.
This Techworld document tabulates details of the ADR and SLR tape formats and includes road map details where available.
This is an OnStream (ex-Philips subsidiary) format, standing for Advanced Digital Recording, aimed at the DDS market. ADR1 was the first generation with its ADR 30 and ADR 50 formats. ADR2.n is the second generation. OnStream went bankrupt in May this year and it looks as if the format has no future. For your reference the format details are:
|ADR 30||ADR 50||ADR2.60||ADR2.120|
|Raw Transfer Rate||to 4MB/sec||to 4MB/sec|
|Compressed Transfer Rate||to 4MB/sec||to 4MB/sec||to 8MB/sec||to 8MB/sec|
|Notes||Reads/writes 8 tracks at once|
ADR2.n has IDE, SCSI or USB2 connectivity. There is a mid-tape directory to reduce access times. ADR2 drives have heads with half the track width of the previous generation, allowing twice the capacity on the same amount of tape. Enhancements to the servo system ensured that the thin film heads followed the tracks on the tape media accurately. OnStream Data recovered from bankruptcy in 2001 with an injection of private capital and became Onstream Data BV, based in the Netherlands. This company has now failed, declaring the Dutch version of Chapter 11 in May this year, signalling a possible consolidation in the low end tape market. Users with ADR drives now need to look ahead for a migration target. SLR might well be a possible destination.
A Tandberg proprietary linear tape format SLR, standing for Scalable Linear Recording, is positioned as a Travan and DDS alternative. It is very scalable with eight existing generations and two further generations proposed in a roadmap. SCSI connectivity is characteristic of each format. Tandberg is Quantum's manufacturing partner for SDLT drives and has a long track record as a tape drive manufacturer. SLR3 and 4 formats are no longer actively marketed by Tandberg.
|Raw Transfer Rate||300KB/sec||300KB/sec||380KB/sec|
|Compressed Transfer Rate||600KB/sec||560KB/sec|
SLR7, 50, 60, 100 and 140 formats use 0.315 inch tape media, which has 26 per cent more recording area than the previous SLR3, 4 and 5 formats. Using a PRML (Partial Response Maximum Likelihood) recording method about 50 per cent more data can be written onto the recordable area. There are 192 data tracks on the SLR60, 100 and 140 formats, but only 72 on the SLR7 format.
|Raw Transfer Rate||3MB/sec||2MB/sec||4MB/sec||5MB/sec|
|Compressed Transfer Rate||6MB/sec||4MB/sec||8MB/sec||10MB/sec|
|Raw Transfer Rate||6MB/sec||16MB/sec||32MB/sec|
|Compressed Transfer Rate||12MB/sec||32MB/sec||64MB/sec|
SLR140 is backwards compatible with all previous SLR formats except SLR3, 4 and 5.