Hi all,
Several messages have been posted here regarding poor VXA performance with
Retrospect. I'd like to clear them up here.
First of all, I personally use one of these drives, and it rocks. It
replaced an aging DDS-2 drive, and I absolutely love the VXA. I use it with
a SuperMac S900 clone (basically a 9500), connected to the mediocre
logic-board SCSI, and I still get over 135 MB/min locally. Two more systems
are also backed up as clients, but that's only over 10baseT, so we won't go
there. ;-)
In DantzLab, running Retrospect 4.1 on a Power Macintosh 9650/350 with Mac
OS 8.5.1, SCSI Manager 4.3, and hardware compression enabled, with a striped
RAID 0 hard drive and the tape drive on separate SCSI-2 cards, we regularly
achieved an average write speed of 283 MB/min to the VXA-1 drive.
To get the best performance out of a VXA drive, be sure you turn OFF
software compression. Yes, Retrospect should ignore software compression
when hardware compression is available, but we missed that in our driver for
the VXA. We will be fixing this soon, but the workaround is to just turn off
software compression.
We will also be adding sync/wide SCSI negotiation to Retrospect in the very
near future. We have been relying on SCSI cards to perform this function,
but many (such as Adaptec cards) are no longer doing this. When no sync/wide
test is performed, the attached tape drive, be it DDS-4, DLT, AIT, VXA,
etc., is assumed to be of lower performance than is really the case.
The VXA is a great drive, and it gets my highest personal recommendation.
With Retrospect configured properly, anyone would be happy with this drive's
performance.
Eric Ullman
Dantz Development
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