On 2006-10-13, Alexander Staubo <alex@xxxxxxxxxxxxxxx> wrote: > On Oct 13, 2006, at 17:13 , Andrew - Supernews wrote: >> Your disk probably has write caching enabled. A 10krpm disk should be >> limiting you to under 170 transactions/sec with a single connection >> and fsync enabled. > > What formula did you use to get to that number? It's just the number of disk revolutions per second. Without caching, each WAL flush tends to require a whole revolution unless the on-disk layout of the filesystem is _very_ strange. You can get multiple commits per WAL flush if you have many concurrent connections, but with a single connection that doesn't apply. > Is there a generic > way on Linux to turn off (controller-based?) write caching? I don't use Linux, sorry. Modern SCSI disks seem to ship with WCE=1 on mode page 8 on the disk, thus enabling evil write caching by default. -- Andrew, Supernews http://www.supernews.com - individual and corporate NNTP services
