Brandon Metcalf wrote:

We've recently moved our pgsql installation and DBs to a Solaris 8
machine with striped and mirrored ufs filesystem that houses the DB
data.  We are now seeing terrible performance and the bottleneck is no
doubt disk I/O.

We've tried modifying a tunables related to ufs, but it doesn't seem
to be helping.

Is there anything we should be looking at that is specifically related
to ufs filesystems on Solaris 8 or possibly something in general that
would improve performance?

Well, Solaris 8 is a bit old now, so I don't remember all the details. But, if memory servers, Solaris 8 still has some "high water" and "lo water" tunables related to the amount of IO can be outstanding to a single file.

Try setting
set ufs:ufs_WRITES=0
in /etc/system and rebooting, which basically says "any amount of disk IO can be outstanding". There's a tunables doc on that explains this option.

Also, logging UFS might help with some of the metadata requirements of UFS as well. So, use "mount -o logging" or add the relevant entry in /etc/vfstab.

Of course, the best thing is Solaris 9 or 10, which would be much better for this sort of thing.

Hope this helps.

-- Alan

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