| From: | "Merlin Moncure" <merlin(dot)moncure(at)rcsonline(dot)com> |
|---|---|
| To: | "Alex Turner" <armtuk(at)gmail(dot)com> |
| Cc: | <pgsql-performance(at)postgresql(dot)org>, "Arshavir Grigorian" <ag(at)m-cam(dot)com> |
| Subject: | Re: Postgres on RAID5 |
| Date: | 2005-03-14 21:18:00 |
| Message-ID: | 6EE64EF3AB31D5448D0007DD34EEB3412A763F@Herge.rcsinc.local |
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| Lists: | pgsql-performance |
Alex Turner wrote:
> 35 Trans/sec is pretty slow, particularly if they are only one row at
> a time. I typicaly get 200-400/sec on our DB server on a bad day. Up
> to 1100 on a fresh database.
Well, don't rule out that his raid controller is not caching his writes.
His WAL sync method may be overriding his raid cache policy and flushing
his writes to disk, always. Win32 has the same problem, and before
Magnus's O_DIRECT patch, there was no way to easily work around it
without turning fsync off. I'd suggest playing with different WAL sync
methods before trying anything else.
Merli
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