Les Mikesell wrote:
Ross S. W. Walker wrote:
Yes, IO starvation can occur under heavy load.
But it should stall the process needing to write, not everything.
There is only 1 disk though and if that disk is busy writing it can't read.
It would be nice if disk manufacturers made full duplex disks with 1 set of heads for writing and another set of heads for reading, but they don't :-(
Don't put database temp tables on system disks (or data
tables for that matter).
How much memory do you have in this box and how big does
the temp directory
usage get?
Why I ask is you could create a tempfs and have mysql use
that, just make sure
you have enough memory that you can spare X (whatever your
temp table usage is)
for a cache filesystem.
You would also notice a dramatic speed increase in MySQL.
I'm not sure the needed temp table space is predictable. I've seen mysql be pretty dumb about how it does a select that joins several tables.
True, but take an average and that should suffice, MySQL will wait if temp space fills up.
-Ross
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