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Date: Mon, 20 Apr 2009 07:39:49 +0200
From: Luca Berra <bluca@comedia.it>
Subject: Re: [linux-lvm] Wierd lvm2 performance problems
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To: linux-lvm@redhat.com

On Sun, Apr 19, 2009 at 05:16:21PM +0200, Sven Eschenberg wrote:
> Unfortunately I don't have the box at hand for 2 days, but I asked md to 
> use a chunksize of 2048K and the /proc/mdstat reported 2048K, last time I 
> checked.
> The LVM hat a phy-extsize of 2M and with the --dataalignment option set to 
> 2M, pvs reported a pe_start value of 2M aswell.

if you have a 2M chunk size, a full stripe is 2M*(N-1), where N-1 is the
number of drives in your array minus redundancy. (i.e. for a 5 drive
raid5 a stripe size would be 8M).

L.

-- 
Luca Berra -- bluca@comedia.it
          Communication Media & Services S.r.l.
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