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Re: relationship of nested stripe sizes, was: Question regarding XFS on

To: Chris Murphy <lists@xxxxxxxxxxxxxxxxx>
Subject: Re: relationship of nested stripe sizes, was: Question regarding XFS on LVM over hardware RAID.
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Mon, 3 Feb 2014 08:30:30 +1100
Cc: "stan@xxxxxxxxxxxxxxxxx Hoeppner" <stan@xxxxxxxxxxxxxxxxx>, xfs <xfs@xxxxxxxxxxx>
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User-agent: Mutt/1.5.21 (2010-09-15)
On Sun, Feb 02, 2014 at 11:09:11AM -0700, Chris Murphy wrote:
> On Feb 1, 2014, at 2:44 PM, Stan Hoeppner <stan@xxxxxxxxxxxxxxxxx>
> wrote:
> > On 2/1/2014 2:55 PM, Chris Murphy wrote:
> >> On Feb 1, 2014, at 11:47 AM, Stan Hoeppner
> >> <stan@xxxxxxxxxxxxxxxxx> wrote:
> > When nesting stripes, the chunk size of the outer stripe is
> > -always- equal to the stripe width of each inner striped array,
> > as I clearly demonstrated earlier:
> 
> Except when it's hardware raid6, and software raid0, and the user
> doesn't know they need to specify the chunk size in this manner.
> And instead they use the mdadm default. What you're saying makes
> complete sense, but I don't think this is widespread knowledge or
> well documented anywhere that regular end users would know this by
> and large.

And that is why this is a perfect example of what I'd like to see
people writing documentation for.

http://oss.sgi.com/archives/xfs/2013-12/msg00588.html

This is not the first time we've had this nested RAID discussion,
nor will it be the last. However, being able to point ot a web page
or or documentation makes it a whole lot easier.....

Stan - any chance you might be able to spare an hour a week to write
something about optimal RAID storage configuration for XFS?

Cheers,

Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx

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