Convert RAID5 to RAID6 in a live system

Hi,

I'm currently in the process of converting a 3 disk RAID5 array into a 4 disk
RAID5 array. I'm using mdadm 3.1.4 and Linux kernel 2.6.35-28-generic
(Ubuntu). My questions now is this conversion save in a live (running) system?
Or is this now allowed/supported?

Thanks.

Best regards,
Stefan
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Re: Convert RAID5 to RAID6 in a live system

On Wed, 23 Mar 2011, Stefan Roese wrote:

> I'm currently in the process of converting a 3 disk RAID5 array into a 4 disk
> RAID5 array. I'm using mdadm 3.1.4 and Linux kernel 2.6.35-28-generic
> (Ubuntu). My questions now is this conversion save in a live (running) system?
> Or is this now allowed/supported?

I guess you wanted to say "4 disk RAID6 array"?

In that case, yes, I have done it on 2.6.32 and mdadm version (something
older) and it went just fine.

Neil wrote about it here .

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Mikael Abrahamsson email: swmike@swm.pp.se
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Re: Convert RAID5 to RAID6 in a live system

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On Wed, 23 Mar 2011 09:07:56 +0100 (CET)
Mikael Abrahamsson wrote:

> On Wed, 23 Mar 2011, Stefan Roese wrote:
>=20
> > I'm currently in the process of converting a 3 disk RAID5 array into a 4
> > disk RAID5 array. I'm using mdadm 3.1.4 and Linux kernel 2.6.35-28-gene=
ric
> > (Ubuntu). My questions now is this conversion save in a live (running)
> > system? Or is this now allowed/supported?
>=20
> I guess you wanted to say "4 disk RAID6 array"?
>=20
> In that case, yes, I have done it on 2.6.32 and mdadm version (something=
=20
> older) and it went just fine.
>=20
> Neil wrote about it here .

Additionally, I suggest that you also check "man mdadm" and note the
"--layout=3Dpreserve" option, if you use it, the RAID5 to RAID6 conversion =
while
adding one disk will happen instantly, without restriping (but only with a
resync of the new drive).

--=20
With respect,
Roman

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Re: Convert RAID5 to RAID6 in a live system

On Wednesday 23 March 2011 09:14:24 Roman Mamedov wrote:
> > > I'm currently in the process of converting a 3 disk RAID5 array into a
> > > 4 disk RAID5 array. I'm using mdadm 3.1.4 and Linux kernel
> > > 2.6.35-28-generic (Ubuntu). My questions now is this conversion save
> > > in a live (running) system? Or is this now allowed/supported?
> >
> > I guess you wanted to say "4 disk RAID6 array"?
> >
> > In that case, yes, I have done it on 2.6.32 and mdadm version (something
> > older) and it went just fine.
> >
> > Neil wrote about it here .
>
> Additionally, I suggest that you also check "man mdadm" and note the
> "--layout=preserve" option, if you use it, the RAID5 to RAID6 conversion
> while adding one disk will happen instantly, without restriping (but only
> with a resync of the new drive).

Thanks. I already started with this conversion, so this "--layout=preserve" is
not an option for me any more. But good to know that this conversion should
work. But its slow - it'll take approx. 4 days with my 2TB drives.

Best regards,
Stefan
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Re: Convert RAID5 to RAID6 in a live system

On Wed, 23 Mar 2011, Stefan Roese wrote:

> Thanks. I already started with this conversion, so this
> "--layout=preserve" is not an option for me any more. But good to know
> that this conversion should work. But its slow - it'll take approx. 4
> days with my 2TB drives.

Also, layout=preserve I guess would make it not a proper RAID6 but a RAID5
with a parity disk. This is not optimal long-term.

The time you mention is normal I'd say.

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Mikael Abrahamsson email: swmike@swm.pp.se
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