Benjamin Krajmalnik wrote:
My data partition is 12 drives in RAID 1+0 (2.7TB) running UFS2.
Vfs.read_max has been set to 32, and no other tuning has been done...
Not having anything to compare it to, I do not know if these are
decent numbers or not -- they are definitely slower than a similar
setup which was posted recently using XFS on Linux, but I have not
found anything in FreeBSD using UFS2 to compare it to. What strikes
me in particular is that the write performance is higher than the read
performance -- I would have intuitively expected it to be the other
way around.
Generally write speed higher than read means that volume read-ahead
still isn't high enough for the OS to keep the disk completely busy.
Try increasing read_max further; I haven't done many such tests on
FreeBSD, but as far as I know settings of 128 and 256 are generally
where read performance peaks on that OS. You should see sequential read
speed go up as you increase that parameter, eventually levelling off.
When you reach that point you've found the right setting.
--
Greg Smith 2ndQuadrant US g...@2ndquadrant.com Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.us
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