scott.marlowe wrote: > I was testing to get some idea of how to speed up the speed of pgbench > with IDE drives and the write caching turned off in Linux (i.e. hdparm -W0 > /dev/hdx). > > The only parameter that seems to make a noticeable difference was setting > wal_sync_method = open_sync. With it set to either fsync, or fdatasync, > the speed with pgbench -c 5 -t 1000 ran from 11 to 17 tps. With open_sync > it jumped to the range of 45 to 52 tps. with write cache on I was getting > 280 to 320 tps. so, not instead of being 20 to 30 times slower, I'm only > about 5 times slower, much better. > > Now I'm off to start a "pgbench -c 10 -t 10000" and pull the power cord > and see if the data gets corrupted with write caching turned on, i.e. do > my hard drives have the ability to write at least some of their cache > during spin down.
Is this a reason we should switch to open_sync as a default, if it is availble, rather than fsync? I think we are doing a single write before fsync a lot more often than we are doing multiple writes before fsync. -- Bruce Momjian | http://candle.pha.pa.us [EMAIL PROTECTED] | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania 19073 ---------------------------(end of broadcast)--------------------------- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faqs/FAQ.html
