Re: SSD + RAID

Bruce Momjian <bruce@momjian.us>

From: Bruce Momjian <bruce@momjian.us>
To: Greg Smith <greg@2ndquadrant.com>
Cc: Merlin Moncure <mmoncure@gmail.com>, Brad Nicholson <bnichols@ca.afilias.info>, Karl Denninger <karl@denninger.net>, Laszlo Nagy <gandalf@shopzeus.com>, pgsql-performance <pgsql-performance@postgresql.org>
Date: 2009-11-28T16:20:56Z
Lists: pgsql-performance

Attachments

Greg Smith wrote:
> Merlin Moncure wrote:
> > I am right now talking to someone on postgresql irc who is measuring
> > 15k iops from x25-e and no data loss following power plug test.
> The funny thing about Murphy is that he doesn't visit when things are 
> quiet.  It's quite possible the window for data loss on the drive is 
> very small.  Maybe you only see it one out of 10 pulls with a very 
> aggressive database-oriented write test.  Whatever the odd conditions 
> are, you can be sure you'll see them when there's a bad outage in actual 
> production though.
> 
> A good test program that is a bit better at introducing and detecting 
> the write cache issue is described at 
> http://brad.livejournal.com/2116715.html

Wow, I had not seen that tool before.  I have added a link to it from
our documentation, and also added a mention of our src/tools/fsync test
tool to our docs.

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

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