Re: Horrible PostgreSQL performance with NFS

On Fri, Jan 13, 2006 at 09:20:13PM +0100, Slawek Zak wrote:
> Hello everyone,
> 
> A couple of days ago I've moved our production database from local
> disks to NetAPP filer serving NFS. Performance for this server dropped
> by factor of 10 if not more. From a happy 10% load, the server hit the
> ceiling and sees load of 100% all the time with runqueue above 30. The
> server is a Sun V40z machine, 4x Opteron 852, 16GB RAM, tuned for 1600
> concurrent connections. I'm running FreeBSD 6.0 BETA5. I don't see any
> problem with the network bandwidth or I/O opcount. Total bandwidth
> generated by the machine tops at 10Mbps. NICs are bge configured for
> 100Mbps full-duplex. Filer hardly notices the traffic. It stays around
> 1% CPU load and 500 NFS ops/s including static file transfers. This
> particular model can handle around 6000 I/Os per second. Trussing
> database processes shows that most of the syscalls are semops. I tried
> to search the archives but couldn't find anything useful for such
> setup.
> 
> I can provide postgresql config. Sysctl knobs remain untouched not
> counting basic NFS tweaking. For mount_nfs I tried to change NFS
> buffer sizes -r -w. I also tried the -L option to keep the lock
> traffic local. On the postgres side, setting fsync = off in
> postgresql.conf. It didn't change a thing.
> 
> Any advice besides "give up on NFS" is most welcome. I need NetAPP
> over NFS for snapshots and easy FS management.

Snapshots of your database files? What do you plan to do with those?

Posgresql does support PITR these days...

-- 
__________________________________________________
"Nothing is as subjective as reality"
Reinoud van Leeuwen    [email protected]
http://www.xs4all.nl/~reinoud
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