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Re: sunit & swidth on RAID-1?

To: mike dentifrice <fluor@xxxxxxxxxxx>
Subject: Re: sunit & swidth on RAID-1?
From: Justin Piszcz <jpiszcz@xxxxxxxxxxxxxxx>
Date: Wed, 11 Feb 2009 12:10:05 -0500 (EST)
Cc: xfs@xxxxxxxxxxx
In-reply-to: <20090211165316.GA4430@dentifrice>
References: <20090211155638.GA3864@dentifrice> <alpine.DEB.1.10.0902111141560.18885@xxxxxxxxxxxxxxxx> <20090211165316.GA4430@dentifrice>
User-agent: Alpine 1.10 (DEB 962 2008-03-14)


On Wed, 11 Feb 2009, mike dentifrice wrote:

Justin Piszcz a dit:
mkfs.xfs will auto-optimize for software-raid arrays for the most
part,  with HW raid on a 3ware controller, tweaking mkfs.xfs does not
help very  much.  with SW raid, at least for raid1 - I use the
defaults.

Thanks for your reply. However, I wonder about the defaults:

        xfs_info /dev/md1 | grep -E '(sunit|swidth)'

Outputs:

       sunit=0      swidth=0 blks, unwritten=1
       sectsz=512   sunit=0 blks

What's the consequence of 0 values in this case?

Greetings,

--
mike dentifrice <fluor@xxxxxxxxxxx>


# xfs_info /dev/md2 | grep -E '(sunit|swidth)'
         =                       sunit=0      swidth=0 blks
         =                       sectsz=512   sunit=0 blks, lazy-count=0

Mine is similar, I guess you would need to benchmark to find out if you were worried about it. I ran multiple copies from a RAID1 (dual raptors) and was able to get the performance of both of the drives combine, so I am not really worried about this setting.

Justin.

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