From: Anton Rommerskirchen <atr@atrsoft.de>
Reply-To: atr@atrsoft.de
Organization: ATRSoft GmbH
To: pgsql-performance@postgresql.org
Subject: Re: Contemplating SSD Hardware RAID
Date: Tue, 21 Jun 2011 20:29:26 +0200
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Am Dienstag, 21. Juni 2011 05:54:26 schrieb Dan Harris:
> I'm looking for advice from the I/O gurus who have been in the SSD game
> for a while now.
>
> I understand that the majority of consumer grade SSD drives lack the
> required capacitor to complete a write on a sudden power loss.  But,
> what about pairing up with a hardware controller with BBU write cache?
> Can the write cache be disabled at the drive and result in a safe setup?
>
> I'm exploring the combination of an Areca 1880ix-12 controller with 6x
> OCZ Vertex 3 V3LT-25SAT3 2.5" 240GB SATA III drives in RAID-10.  Has
> anyone tried this combination?  What nasty surprise am I overlooking here?
>
> Thanks
> -Dan

Wont work.

period.

long story: the loss of the write in the ssd cache is substantial.=20

You will loss perhaps the whole system.

I have tested since 2006 ssd - adtron 2GB for 1200 Euro at first ...=20

i can only advice to use a enterprise ready ssd.=20

candidates: intel new series , sandforce pro discs.

i tried to submit a call at apc to construct a device thats similar to a=20
buffered drive frame (a capacitor holds up the 5 V since cache is written=20
back) , but they have not answered. so no luck in using mainstream ssd for=
=20
the job.=20

loss of the cache - or for mainstream sandforce the connection - will resul=
t=20
in loss of changed frames (i.e 16 Mbytes of data per frame) in ssd.

if this is the root of your filesystem - forget the disk.

btw.: since 2 years i have tested 16 discs for speed only. i sell the disc=
=20
after the test. i got 6 returns for failure within those 2 years - its real=
ly=20
happening to the mainstream discs.
=20
=2D-=20
Mit freundlichen Gr=FCssen
Anton Rommerskirchen