Re: Investigating IO Saturation

Joshua D. Drake wrote:

> Brad Nicholson wrote:
>
>> I'm investigating a potential IO issue.  We're running 7.4 on AIX
>> 5.1.  During periods of high activity (reads, writes, and vacuums),
>> we are seeing iostat reporting 100% disk usage.  I have a feeling
>> that the iostat numbers are misleading.  I can make iostat usage jump
>> from less than 10% to greater than 95% by running a single vacuum
>> against a moderate sized table (no noticeable change in the other
>> activity).
>>
> Well that isn't surprising. Vacuum is brutal especially on 7.4 as that
> is pre background writer. What type of IO do you have available (RAID,
> SCSI?)
>
Data LUN is RAID 10, wal LUN is RAID 1.


--
Brad Nicholson  416-673-4106    bnichols@ca.afilias.info
Database Administrator, Afilias Canada Corp.