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Re: SSD + RAID

From: Matthew Wakeling <matthew(at)flymine(dot)org>
To: Greg Smith <greg(at)2ndquadrant(dot)com>
Cc: Laszlo Nagy <gandalf(at)shopzeus(dot)com>, pgsql-performance <pgsql-performance(at)postgresql(dot)org>
Subject: Re: SSD + RAID
Date: 2009-12-08 14:22:17
Message-ID: alpine.DEB.2.00.0912081421120.25000@aragorn.flymine.org (view raw or flat)
Thread:
Lists: pgsql-performance
On Fri, 13 Nov 2009, Greg Smith wrote:
> In order for a drive to work reliably for database use such as for 
> PostgreSQL, it cannot have a volatile write cache.  You either need a write 
> cache with a battery backup (and a UPS doesn't count), or to turn the cache 
> off.  The SSD performance figures you've been looking at are with the drive's 
> write cache turned on, which means they're completely fictitious and 
> exaggerated upwards for your purposes.  In the real world, that will result 
> in database corruption after a crash one day.

Seagate are claiming to be on the ball with this one.

http://www.theregister.co.uk/2009/12/08/seagate_pulsar_ssd/

Matthew

-- 
 The third years are wandering about all worried at the moment because they
 have to hand in their final projects. Please be sympathetic to them, say
 things like "ha-ha-ha", but in a sympathetic tone of voice 
                                        -- Computer Science Lecturer

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