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From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Greg Smith <greg(at)2ndquadrant(dot)com>
Cc: Merlin Moncure <mmoncure(at)gmail(dot)com>, Brad Nicholson <bnichols(at)ca(dot)afilias(dot)info>, Karl Denninger <karl(at)denninger(dot)net>, Laszlo Nagy <gandalf(at)shopzeus(dot)com>, pgsql-performance <pgsql-performance(at)postgresql(dot)org>
Subject: Re: SSD + RAID
Date: 2009-11-28 16:20:56
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
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 

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(at)momjian(dot)us>

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

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