A quick and easy performance improvement
Richard Lynch
rich at mail.wvnet.edu
Wed Jul 26 16:00:01 IST 2006
denis at croombs.org wrote:
>>I thought I'd post to the list about a change I made yesterday which
>>provided a huge boost in system's performance.
>>
>>By far the largest amount of time spent in the life of a disk I/O
>>operation is seek time. Seek time is the amount of time it takes to
>>move the disk R/W heads from one cylinder to another. The /var/spool
>>filesystem is where the inbound and outbound mail queues are located.
>>Note also that the Bayes database is accessed heavily when analyzing a
>>message.
>>
>>Like many installations we have our root filesystem (/) and /var
>>filesystem on separate partitions on a single hard drive. The default
>>location for the SpamAssassin bayes database is in /root/.spamassassin/
>>which is on the rootfs. Moving the bayes database to
>>/var/spool/spamassassin resulted in a huge decrease in IOWait time. In
>>our case it was an order of magnitude reduction. For example, IOWait
>>percentages went from 30% to 3%. IOWait is the percentage of time the
>>processor is waiting on an I/O operation to complete. Our mail queues
>>no longer get behind and throughput is outstanding!
>>
>>
>>
>I would also assume having them on different hard drives would give an
>even larger increase in throughput ?
>
>Regards
>
>Denis
>
>
>
Most certainly, however this would depend on what else is happening on
the two drives.
-- Rich
--
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