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Re: sunit & swidth on RAID-1?

To: xfs@xxxxxxxxxxx
Subject: Re: sunit & swidth on RAID-1?
From: Michael Monnerie <michael.monnerie@xxxxxxxxxxxxxxxxxxx>
Date: Wed, 11 Feb 2009 22:12:28 +0100
In-reply-to: <20090211165316.GA4430@dentifrice>
Organization: it-management http://it-management.at
References: <20090211155638.GA3864@dentifrice> <alpine.DEB.1.10.0902111141560.18885@xxxxxxxxxxxxxxxx> <20090211165316.GA4430@dentifrice>
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On Mittwoch 11 Februar 2009 mike dentifrice wrote:
>         sunit=0      swidth=0 blks, unwritten=1
>         sectsz=512   sunit=0 blks
>
> What's the consequence of 0 values in this case?

XFS then knows that 512 byte (aka sector) alignment is sufficient, as 
RAID-1 will only write 512b to each disk and does not need full stripe 
unit writes like RAID-4/5/6 need. Therefore performance is better with 
the values you have.

mfg zmi
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