Date: Fri, 13 Jan 2006 21:20:13 +0100 From: Slawek Zak <slawek.zak@gmail.com> To: freebsd-database@freebsd.org, freebsd-performance@freebsd.org Subject: Horrible PostgreSQL performance with NFS Message-ID: <787bbe1c0601131220j7b3a052ege5fe4683156312a7@mail.gmail.com>
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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. TIA, /S -- Sławek Żak / UNIX Systems Administrator
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