Horrible PostgreSQL performance with NFS
Reinoud van Leeuwen
reinoud.v at n.leeuwen.net
Fri Jan 13 13:51:22 PST 2006
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
> 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 reinoud.v at n.leeuwen.net
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