Re: fsync = true beneficial on ext3?

I can see you never took statistics...

On Mon, 9 Feb 2004, Jim C. Nasby wrote:

> Actually, I don't think even that is a valid test. The absence of a
> failure doesn't mean one can't occur in this case. Doesn't matter if you
> try the test 1 or 10,000 times; the test will only be conclusive if you
> actually see a failure.
>
> On Mon, Feb 09, 2004 at 10:19:15AM -0700, scott.marlowe wrote:
> > On Sun, 8 Feb 2004, 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?
> > >
> > > 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?
> >
> > With all the other posts on this topic, I just want to point out that it's
> > all theory until you build your machine, set it up, initiate a hundred or
> > so parallel transactions, and pull the plug in the middle.
> >
> > Without pulling the plug, you just don't know for sure.  And you need to
> > do it a few times, in case your machine "got lucky" once and might fail on
> > subsequent power fails.
> >
> >
> > ---------------------------(end of broadcast)---------------------------
> > TIP 4: Don't 'kill -9' the postmaster
> >
>
>