Re: SSD + RAID

On Tue, Nov 17, 2009 at 1:51 PM, Greg Smith <greg(at)2ndquadrant(dot)com> 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

Sure, not disputing that...I don't have one to test myself, so I can't
vouch for the data being safe. But what's up with the 400 iops
measured from bonnie++? That's an order of magnitude slower than any
other published benchmark on the 'net, and I'm dying to get a little
clarification here.

merlin