On 12/4/06, Jason J. W. Williams <[EMAIL PROTECTED]> wrote:
Hi Daniel,
Thank you very much for your help and advice. After some examination,
we discovered a couple of things. It looks like our storage array
layout was really bad for the IOPS MySQL was throwing at it, as a
result the InnoDB transactions started to back-up under heavy load.
Changing the array layout from RAID-5 to RAID-1 as well as moving the
logs to their own spindles corrected the issue. Also, moving the
InnoDB fsync log flushing interval from every commit to a 2 second
interval helped dramatically.
We found the storage was the problem by looking at SHOW INNODB STATUS
while looking at the SCSI IOP latency.
Does this sound reasonable to you?
Disk IO is one of innodb's bottleneck anyway, but I doubt this could
hurt performance as you suggested, making it unusable. You're the one
with access to the system, and thus the only one who can test it and
be sure ;) . Making a RAID 5 should increase read performance (if you
calculate the best segment size), but the write operations would be
not as fast as with a RAID 1, and you're risking data loss if more
than one of your disks go away. I never trade security for speed, and
if I were you I would check for another option. What's the most
frequent operation (read/write) on your tables?
Anyway, glad you solved your problem.
Just out of curiosity, what is your filesystem?
--
Daniel da Veiga
Computer Operator - RS - Brazil
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