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Message-ID: <4C4A9452.9070100@gmail.com>
Date: Sat, 24 Jul 2010 09:20:50 +0200
From: Yeb Havinga <yebhavinga@gmail.com>
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To: pgsql-performance@postgresql.org
Subject: Testing Sandforce SSD
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Hello list,

Probably like many other's I've wondered why no SSD manufacturer puts a 
small BBU on a SSD drive. Triggered by Greg Smith's mail 
http://archives.postgresql.org/pgsql-performance/2010-02/msg00291.php 
here, and also anandtech's review at 
http://www.anandtech.com/show/2899/1 (see page 6 for pictures of the 
capacitor) I ordered a SandForce drive and this week it finally arrived.

And now I have to test it and was wondering about some things like

* How to test for power failure? I thought by running on the same 
machine a parallel pgbench setup on two clusters where one runs with 
data and wal on a rotating disk, the other on the SSD, both without BBU 
controller. Then turn off power. Do that a few times. The problem in 
this scenario is that even when the SSD would show not data loss and the 
rotating disk would for a few times, a dozen tests without failure isn't 
actually proof that the drive can write it's complete buffer to disk 
after power failure.

* How long should the power be turned off? A minute? 15 minutes?

* What filesystem to use on the SSD? To minimize writes and maximize 
chance for seeing errors I'd choose ext2 here. For the sake of not 
comparing apples with pears I'd have to go with ext2 on the rotating 
data disk as well.

Do you guys have any more ideas to properly 'feel this disk at its teeth' ?

regards,
Yeb Havinga