Product Reviews

The fact that vendors have signified they will no longer be developing the DAT-DDS format leaves a large window of opportunity for tape drive manufacturers in the small to medium business sector. Although comparatively costly, Sony is hoping to harvest some of this market with its latest AIT-3 drives. The new SLR7 from Tandberg Data looks a better bet as, although it offers identical transfer rates and capacities to the DDS-4 format, it's part of a comprehensive range of SLR (scalable linear recording) products and consequently offers a wide upgrade path to higher speeds and capacities.

Initially, the SLR7 looks identical to the older SLR40 but it's aimed at the budget conscious. It's only backward read compatible with SLR5 media and doesn't have the head servo system used by the SLR40, which allows it to accurately track tape movement.

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The SLR7 uses a dual-channel TF/MR (thin film/magneto resistive) head and employs Overland Data's VR2 (variable rate randomizer) technology. Implemented on a chip, VR2 uses a variant of PRML (partial response maximum likelihood), which allows capacity and performance to be increased without changing the media or drive design. The drive uses a simple load mechanism that doesn't remove the tape from the cartridge. Rather than wrap it around multiple rollers, a single capstan inside the cartridge keeps a slight pressure on the tape to move it into contact with the head. This tender treatment of media will result in greater reliability and longevity.

For testing, the drive was installed on a Pentium III/866 system running Windows 2000 Server. Under Veritas Backup Exec 8.6 and Computer Associates ARCserve 2000, the drive delivered close to its quoted native transfer rates. While securing a 7Gb mixture of files it returned average speeds 177Mbytes/min and 187Mbytes/min respectively, and it restored the test data to its original location at rates of 182Mbytes/min and 194Mbytes/min.

Many companies that invested in the DDS format will soon be looking for an alternative backup solution and should consider the SLR7. Price-wise, it compares well with DSS-4, delivering almost identical transfer rates, yet it offers a solid upgrade path, as both the current SLR60 and SLR100 drives are backward read compatible with SLR7 media.