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From: Marian Csontos <mcsontos@redhat.com>
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Date: Tue, 11 Apr 2017 19:37:36 +0200
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Subject: Re: [linux-lvm] stripped LV with segments vs one segment
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To: lejeczek <peljasz@yahoo.co.uk>, linux-lvm@redhat.com

On 04/10/2017 04:27 PM, lejeczek wrote:
>
>
> On 10/04/17 13:27, Marian Csontos wrote:
>> On 04/10/2017 01:16 PM, lejeczek wrote:
>>
>>>
>>> I had 3 stripe LV, you know, three PVs, and wanted the LV to have 4
>>> stripes, wanted to add 4th PV, you can see it from above lvdisplay.
>>
>> What you want is "reshape" not extend. This was committed as RAID
>> feature to 2.02.169, but it is still somewhat experimental. You would
>> need to convert stripe LV to RAID0 (aka takeover) and then reshape.
>>
> convert from stipe to raid0 would not preserve stripe sizes? is this
> correct?

It should keep stripe size and if it does not it is a bug.

> nor it would:
>
> -I/--stripesize not allowed for LV dellH200.InternalB/0 when converting
> from striped to raid0.

As it says, the option is simply not allowed. Also it would be 
meaningless - one can not change stripe size while converting stripe to 
raid0. At least not in RHEL-7.3 (lvm2-2.02.166). This is supposed to 
work in upstream/2.02.169, but keep in mind that is a new feature, and 
it is altering data, so better keep a working backup.

>
>   LVM version:     2.02.166(2)-RHEL7 (2016-11-16)
>   Library version: 1.02.135-RHEL7 (2016-11-16)
>   Driver version:  4.35.0