#18 Roll Tape - The “Tests”

This page provide the results of informal tests between the ADR and VXA formats

Let’s start by saying that these tests are absolutely non–rigorous! I made no attempt to “level the playing field,” so to speak. All I wanted to see was typical backup performance in my computer with a range of file sizes. Unfortunately, the two evaluation units arrived many months apart, so I couldn’t use the same files on each unit. Also understand that the OnStream product was a SCSI-2 device attached to an Adaptec PCI SCSI HBA, the 3940UW dual channel model. The Ecrix product was a FireWire model, so we’re talking “apples and oranges” here: two very different devices.

Given those conditions, below is the first screen shot, Figure 1. It’s from Dantz Development’s Retrospect application, version 4.3a, and you can see the performance average for that run was 73 MegaBytes per minute. That was an average result with the configuration I had in place. The volume being backed up is a Seagate mechanism in a 3 slot JBOD on the same SCSI chain as the OnStream mechanism.

 



Figure 1


Now on to Figure 2, a screen shot of the log window showing the VXA drive at work…You can see that, this time, I backed up three logical volumes. Two of them, E Diode and Joshua, are partitions on the ATA internal boot volume. The third, Atlas, is another Seagate SCSI-2 mechanism in the same JBOD. Again, typical results in my system, with a range from 114.2 to 142.9 MB/min. and the average being 131.

 



Figure 2




What conclusions can be derived from these tests? Only that, on my system, the VXA drive was a good bit faster and beat on the tape a good bit less than the OnStream. The Ecrix is also acoustically quiter, for what that’s worth.

Something to consider with both of these products is that they are both single source formats. There are no other vendors, no second source manufacturers, that make the drives. In general, this is not a good thing as backups tend to sit in storage for a long time and are pressed into service only in dire circumstances. If the mechanism is dead and the manufacturer has gone by the wayside, then you may be in trouble. Also, where there’s no competition, blank media tends to be more expensive. Caveat emptor.

 

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That’s all for this installment, so head back to Bitstream #18…