On Friday, Apr 30, 2004, at 05:33 Australia/Sydney, Ted Byrne wrote:
AIX client v. 5.1.5.5 AIX server v. 5.1.8.0 AIX version 5.2.0.0
We have a customer who is experiencing discrepancies in performance between large-file cold backups of Oracle data and LV image backups, both sent over the SAN to LTO-2 tape drives. On the lv image backups, they are getting about 70 MB/s sustained. For the B/A client backups, they are getting less than 30 MB/s.
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I have a PMR open with IBM regarding this issue. Is anyone aware of a way to control the block size used for reads by the TSM client?
To the best of my knowledge, you can't. AIX Filesystem I/Os, where DIRECTIO is not involved, go through the AIX VM subsystem - and may get split, joined and otherwise mangled on the way through. Some of this is tuneable through /usr/samples/kernel/vmtune, although much there is black magic.
I'm assuming DIRECTIO is not involved (as an AIX mount option)?
Just a hunch, but what do your filesystem parameters look like on the
client ("lsfs -q /blah")?Cheers, -- Paul Ripke Unix/OpenVMS/TSM/DBA I love deadlines. I like the whooshing sound they make as they fly by. -- Douglas Adams
