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Re: [Veritas-bu] DSSU destaging performance?
2007-11-30 01:50:32
A common cause of drive performance problems is using too many tape drives and not having a media server and disk subsystem that can push data fast enough to the tape drives.
Start off by using only one tape drive and ensure the buffer setting are 256K.
use "iostat -xdnz 1" to examine the drive performance.
One way to validate the performance of entire path from DSSU to tape is to use "dd" and iostat.
something like "dd -bs 256 -if /dev/null -of /dev/rmt/??cbn (use a blank tape!!!)
In another window run iostat to look at the stats.
This will tell you the performance of the tape drives and SAN excluding the disk subsystem. If you are a critical thinker, extrapolate from what I said to isolate and test out the other path components.
Jonathan Marianu
Sent from AT&T Blackberry 8820
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