VxFS tunables for Oracle on HP/UX
- From: "Jesse, Rich" <Rich.Jesse@xxxxxxxxxxxxxxxxx>
- To: "ORACLE-L (E-mail)" <oracle-l@xxxxxxxxxxxxx>
- Date: Mon, 12 Apr 2004 12:23:13 -0500
Hey all,
In implementing a SAN on a new HP/UX 11.11 system, I'm not particularly
blown away by the I/O performance from Oracle or otherwise, with or without
the 2GB writeback caching. So, I'm looking to see what our tunables are.
One batch of tunables are the VxFS "vol_xxxx" kernel parameters. Has anyone
messed with these for maximizing I/O performace for Oracle? In particular,
it seems that the default value for "vol_maxio" may be inadequate for
Oracle, but I haven't been able to find a definitive guide as to how to
determine a proper value. The Most Venerable Gaja has some references to
this in his "Implementing RAID on Oracle" whitepaper
(http://www.revealnet.com/pipelines/dba/archives/Raid1.pdf), but the
calculation of the value of vol_maxio is a little vague, suggesting either
2048 or 8192, but not being definitive as to how to determine which is
"better" (pages 16-17 of the whitepaper).
I also found an HP-UX guide to the "vol_xxxx" parameters at docs.hp.com, but
there are no suggested values for vol_maxio and most other params. One
thing it does say is that "The value of voliomem_maxpool_sz must be at least
10 times greater than the value of vol_maxio." But since the UOMs are
different between the two params -- vol_maxio is in 512-byte blocks and
voliomem_maxpool_sz is in bytes -- it doesn't say if the specified value is
to be 10 times greater or if it's the number of bytes that's supposed to be
10x.
I need to keep in mind that VxFS is used both for DBs on the SAN as well as
software and other files on the local SCSI drives. I imagine that the DB
I/O performance would be more important, though.
Thoughts, anyone?
Rich
Rich Jesse System/Database Administrator
rich.jesse@xxxxxxxxxxxxxxxxx QuadTech, Sussex, WI USA
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