Re: SSD + RAID

Ron Mayer wrote:
> Bruce Momjian wrote:
> > Greg Smith wrote:
> >> Bruce Momjian wrote:
> >>> I thought our only problem was testing the I/O subsystem --- I never
> >>> suspected the file system might lie too.  That email indicates that a
> >>> large percentage of our install base is running on unreliable file
> >>> systems --- why have I not heard about this before?
> >>>
> >> he reason why it
> >> doesn't bite more people is that most Linux systems don't turn on write
> >> barrier support by default, and there's a number of situations that can
> >> disable barriers even if you did try to enable them.  It's still pretty
> >> unusual to have a working system with barriers turned on nowadays; I
> >> really doubt it's "a large percentage of our install base".
> >
> > Ah, so it is only when write barriers are enabled, and they are not
> > enabled by default --- OK, that makes sense.
>
> The test program I linked up-thread shows that fsync does nothing
> unless the inode's touched on an out-of-the-box Ubuntu 9.10 using
> ext3 on a straight from Dell system.
>
> Surely that's a common config, no?

Yea, this certainly suggests that the problem is wide-spread.

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +