From: | Mark Mielke <mark(at)mark(dot)mielke(dot)cc> |
---|---|
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: | 2009-11-17 20:09:58 |
Message-ID: | 4B030316.7040306@mark.mielke.cc |
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Lists: | pgsql-performance |
On 11/17/2009 01:51 PM, 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
>
I've been following this thread with great interest in your results...
Please continue to share...
For write cache issues - is it possible that the reduced power
utilization of SSD allows for a capacitor to complete all scheduled
writes, even with a large cache? Is it this particular drive you are
suggesting that is known to be insufficient or is it really the
technology or maturity of the technology?
Cheers,
mark
--
Mark Mielke<mark(at)mielke(dot)cc>
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