On 17 Srpen 2011, 21:22, Ogden wrote: >> This is a very important point. I've found on most machines with >> hardware caching RAID and 8 or fewer 15k SCSI drives it's just as >> fast to put it all on one big RAID-10 and if necessary partition it to >> put the pg_xlog on its own file system. After that depending on the >> workload you might need a LOT of drives in the pg_xlog dir or just a >> pair. Under normal ops many dbs will use only a tiny % of a >> dedicated pg_xlog. Then something like a site indexer starts to run, >> and writing heavily to the db, and the usage shoots to 100% and it's >> the bottleneck. > > I suppose this is my confusion. Or rather I am curious about this. On my > current production database the pg_xlog directory is 8Gb (our total > database is 200Gb). Does this warrant a totally separate setup (and > hardware) than PGDATA? This is not about database size, it's about the workload - the way you're using your database. Even a small database may produce a lot of WAL segments, if the workload is write-heavy. So it's impossible to recommend something except to try that on your own. Tomas -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
