X-Serve G5 internal drive backup to VXA-2 via FW800...average speed?

[mgb123]

Is there any place that I might find the average backup speeds for a VXA-2 tape drive?

 

I'm currently seeing anywhere from 280-350 mb/sec on our internal 2 drive mirrored raid set on our G5 X-Serve.

 

I'd really like to know if that's high/low/average.

[rhwalker]

We are seeing about 340-360 mb/sec on our internal 3x250 GB RAID 5 on Apple Hardware RAID to Exabyte VXA-2 1x10 1u PacketLoader (SCSI) on ATTO UL4D for our Xserve G5 2.0 GHz.

 

Not your same configuration, but numbers seem similar.

[mgb123]

Thanks for the reply. I'd seen numbers in the 1400's in the windows forums, so I was a little curious (they were backing up to hard drives...).

[SimonHobson]

Quote:

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Thanks for the reply. I'd seen numbers in the 1400's in the windows forums, so I was a little curious (they were backing up to hard drives...).

 

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Doh, hard drives are a LOT faster than tape ! I've seen 1800MB/min regularly from a Linux client to FW800 hard disks on a 1.8GHz xServe, but about 400 max to SLR100 (about the rated streaming data rate for the drive with a little bit of compression taking place.

 

Looking at http://www.exabyte.com/products/products/specifications.cfm?id=400, I see the quoted transfer rate as 21.6GB/hr, which is about 360MB/min (coincidentally the same as the SLR100). You can multiply that by whatever compression ration you get and that will be your limit - reached only when copying large files where the overhead of cataloging etc is low. If anything holds up the data (slow client, lots of small files causing a lot of houskeeping, etc) to the extent that you cannot feed the drive at it's streaming rate, then then the tape will stop, back up, and set off again when more data is available - this drops throughput VERY dramatically.