From: Hannes Dorbath <light@theendofthetunnel.de>
To: pgsql-general@postgresql.org
Subject: Arguments Pro/Contra Software Raid
Date: Tue, 09 May 2006 11:16:45 +0200
Message-ID: <e3pmkc$12mk$1@news.hub.org> (raw)
Hi,
I've just had some discussion with colleagues regarding the usage of
hardware or software raid 1/10 for our linux based database servers.
I myself can't see much reason to spend $500 on high end controller
cards for a simple Raid 1.
Any arguments pro or contra would be desirable.
From my experience and what I've read here:
+ Hardware Raids might be a bit easier to manage, if you never spend a
few hours to learn Software Raid Tools.
+ There are situations in which Software Raids are faster, as CPU power
has advanced dramatically in the last years and even high end controller
cards cannot keep up with that.
+ Using SATA drives is always a bit of risk, as some drives are lying
about whether they are caching or not.
+ Using hardware controllers, the array becomes locked to a particular
vendor. You can't switch controller vendors as the array meta
information is stored proprietary. In case the Raid is broken to a level
the controller can't recover automatically this might complicate manual
recovery by specialists.
+ Even battery backed controllers can't guarantee that data written to
the drives is consistent after a power outage, neither that the drive
does not corrupt something during the involuntary shutdown / power
irregularities. (This is theoretical as any server will be UPS backed)
--
Regards,
Hannes Dorbath
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To: pgsql-performance@postgresql.org
Cc: light@theendofthetunnel.de, pgsql-general@postgresql.org
Subject: Re: Arguments Pro/Contra Software Raid
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