From: Mark Mielke <mark@mark.mielke.cc>
To: david@lang.hm
Cc: Florian Weimer <fw@deneb.enyo.de>
Cc: Fernando Hevia <fhevia@ip-tel.com.ar>
Cc: pgsql-performance <pgsql-performance@postgresql.org>
Subject: Re: With 4 disks should I go for RAID 5 or RAID 10
Date: Wed, 26 Dec 2007 16:59:45 -0500
Message-ID: <4772CED1.2070808@mark.mielke.cc> (raw)
In-Reply-To: <Pine.LNX.4.64.0712261452410.11785@asgard.lang.hm>
References: <0f8201c847f6$08e15090$8f01010a@iptel.com.ar>
<Pine.LNX.4.64.0712261317320.11785@asgard.lang.hm>
<87zlvxnpkl.fsf@mid.deneb.enyo.de>
<Pine.LNX.4.64.0712261452410.11785@asgard.lang.hm>
david@lang.hm wrote:
> I could see a raid 1 array not doing consistancy checking (after all,
> it has no way of knowing what's right if it finds an error), but since
> raid 5/6 can repair the data I would expect them to do the checking
> each time.
Your messages are spread across the thread. :-)
RAID 5 cannot repair the data. I don't know much about RAID 6, but I
expect it cannot necessarily repair the data either. It still doesn't
know which drive is wrong. In any case, there is no implementation I am
aware of that performs mandatory consistency checks on read. This would
be silliness.
Cheers,
mark
--
Mark Mielke <mark@mielke.cc>
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To: pgsql-performance@postgresql.org
Cc: mark@mark.mielke.cc, david@lang.hm, fw@deneb.enyo.de, fhevia@ip-tel.com.ar
Subject: Re: With 4 disks should I go for RAID 5 or RAID 10
In-Reply-To: <4772CED1.2070808@mark.mielke.cc>
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