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From: Stuart D Gathman <stuart@bmsi.com>
To: linux-lvm@redhat.com
Subject: Re: [linux-lvm] Convert striped lv to single pv on another disk?
Date: Fri, 14 Dec 2012 13:33:09 -0500	[thread overview]
Message-ID: <50CB70E5.6010002@bmsi.com> (raw)
In-Reply-To: <50CA0492.1050906@redhat.com>

On 12/13/2012 11:38 AM, Bryn M. Reeves expounded in part:
> On 13/12/12 16:11, Gianluca Cecchi wrote:
>> I found in another thread that the resulting LV with pvmove remains a
>> striped one on only one disk as far as its structure is concerned...
>> with degraded performance...
>> Have you an example of pvmove command options to test to execute based
>> on my test?
>> So that I can verify with my loop devices?
> Yes, you're right. You will end up with both stripes still present but
> on a single disk.
>
> The best I could do using pvmove was to move individual extents around
> (!) to make the LV contiguous on-disk. Of course, this doesn't remove
> the striping and inflates the number of segments since each pair of
> striped extents effectively becomes a segment.
>
> The lvconvert command also still accepts a -i <n> parameter but doesn't
> do anything useful with it and doesn't report an error.
>
Could you create an asymmetrical mirror - where one leg is striped and 
the other is linear?  Then you can just sync the mirror and delete the 
striped leg.   I could even see operating with such a mirror - call it 
RAID �.  Reads would prefer the striped side, and the mirror is there in 
case one of the stripes fails, while requiring only 1 additional drive 
and degrading only write performance.

RAID10 over the 3 drives is probably better, though.

      reply	other threads:[~2012-12-14 18:33 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-12-13 13:32 [linux-lvm] Convert striped lv to single pv on another disk? Gianluca Cecchi
2012-12-13 15:28 ` Gianluca Cecchi
2012-12-13 15:39   ` Bryn M. Reeves
2012-12-13 16:11     ` Gianluca Cecchi
2012-12-13 16:38       ` Bryn M. Reeves
2012-12-14 18:33         ` Stuart D Gathman [this message]

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