Tandberg Data DLT VS160
By Dave Mitchell | Published: 00:00, 16 May 2003
Introduced way back in 1999 by Benchmark Storage Innovations, the original DLT1 format was offered as a cost effective small to medium level backup solution that combined the performance of DLT7000 with the capacity of DLT8000 but claimed to only cost the same as DDS-4.
This remarkable feat was achieved by licensing the original DLT (digital linear tape) technology from Quantum and modifying it to create a new tape drive. A two-channel, magneto-resistive (MR) head replaced the DLT4000 ferrite head while using four tape rollers instead of six, a soft-load mechanism and a lightweight mounting plate further reduced manufacturing costs. The VS80 was the next step but this didn’t represent a new generation as it only offered the same DLT1 drive in a half height package making it more suited to PC-based server backup.
Three years down the line and the VS160 delivers a solid boost to the format with native capacity doubling to 80GB while performance goes up from 3MB/sec to a far more impressive 8MB/sec. Capacity has been improved by increasing the number of tracks from 168 to 240 and the recording density from 123Kb/inch to 175Kb/inch.
The VS80 was also one of few tape drives still using the older RLL (run length limited) encoding method and this has finally been replaced with the more common PRML (partial response maximum likelihood) which the majority of tape drives now use.
For performance testing we hooked the VS160 up to a dedicated Adaptec Ultra160 SCSI controller in a Pentium III 866MHz system with 768MB of memory and running Windows 2000 Server. An Ultra160 hard disk subsystem provided storage and we created a 5GB mixture of data to represent the average departmental server. Under Computer Associates ARCserve 9 the VS160 achieved slightly better than its quoted native transfer rate by delivering an average of 509MB/min during backup and verification while a full restoration returned 479MB/min. It also delivered similar speeds under the control of Veritas Backup Exec 9 with this software reporting 506MB/min, 508MB/min and 481MB/min for the three respective tasks.
The VS160 clearly delivers the quoted native performance and more but there are a number of issues with this format, not least the amount of time it took to produce a second generation. The original claim that DLT1 would cost no more than DDS was never met and the comparatively high price of the VS160 makes it less cost-effective as an entry-level server backup product.
There are also compatibility issues to be considered as the VS160 is only backward read-compatible with the earlier DLT1 and VS80 tapes so your investment in existing media is nullified. However, those companies that embraced DLT1 and VS80 will no doubt be relieved to see this next generation as it delivers solid improvements over its predecessors and they will be further heartened by the fact that Quantum has since acquired Benchmark Storage Innovations.