JM wrote: > Would a battery backed Card do the trick? No because the fsync causes the data to hit the card. Without the fscync, the data could remain only in the kernel cache. --------------------------------------------------------------------------- > > > > > On Tuesday 10 February 2004 00:42, Bruce Momjian wrote: > > Ed L. wrote: > > > I'm curious what the consensus is, if any, on use of fsync on ext3 > > > filesystems with postgresql 7.3.4 or later. I did some recent > > > performance tests demonstrating a 45%-70% performance improvement for > > > simple inserts with fsync off on one particular system. Does fsync = > > > true buy me any additional recoverability beyond ext3's journal recovery? > > > > Yes, it does. Without fsync, you can't be sure the data has been pushed > > to the disk drive in case of an OS crash or power failure. > > > > > If we write something without sync'ing, presumably it's immediately > > > journaled? So even if the DB crashes prior to fsync'ing, are we fully > > > recoverable? I've been running a few pgsql clusters on ext3 with fsync = > > > false, suffered numerous OS crashes, and have yet to lose any data or see > > > any corruption from any of those crashes. Have I just been lucky? > > > > The fsync makes sure it hits the drive, rather than staying in the > > kernel cache during an OS failure. > -- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (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 4: Don't 'kill -9' the postmaster
