SLR to the rescue?

This Techworld document tabulates details of the ADR and SLR tape formats and includes road map details where available. ADR
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 Capacity	c15GB	c25GB	30GB	60GB
Compressed Capacity	30GB	50GB	60GB	120GB
Raw Transfer Rate			to 4MB/sec	to 4MB/sec
Compressed Transfer Rate	to 4MB/sec	to 4MB/sec	to 8MB/sec	to 8MB/sec
Date available	c1999	Ic1999	2001	2001
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. SLR
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.

	SLR3	SLR4	SLR5
Raw Capacity	1.2GB	2.5GB	4GB
Compressed Capacity		5GB	8GB
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.

	SLR7	SLR50	SLR60	SLR100
Raw Capacity	20GB	25GB	30GB	50GB
Compressed Capacity	40GB	50GB	60GB	100GB
Raw Transfer Rate	3MB/sec	2MB/sec	4MB/sec	5MB/sec
Compressed Transfer Rate	6MB/sec	4MB/sec	8MB/sec	10MB/sec

SLR140 was announced in September, 2003. It had been called SLR150 previously, implying a compressed capacity of 150GB. In the event it reached 140GB. The roadmap shows two further generations. The planned SLR200 and SLR400 capacity targets are just that; targets, and may not be fully realised.

	SLR140	SLR200	SLR400
Raw Capacity	70GB	100GB	200GB
Compressed Capacity	140GB	200GB	400GB
Raw Transfer Rate	6MB/sec	16MB/sec	32MB/sec
Compressed Transfer Rate	12MB/sec	32MB/sec	64MB/sec
Date Available	2003	2004?	2005/6

SLR140 is backwards compatible with all previous SLR formats except SLR3, 4 and 5.