Convert RAID 5 to RAID 6 while reducing array size

Hi,
I'm trying to convert a 6 device raid5 into a raid6. The 6th device was added into the Raid 5 by mistake instead of a grow operation to convert it into a RAID 6. As such the md device is not being used beyond the size that it had when it was a 5 device raid5.

Can this be done in a single grow step by specifying the reduced size (--array-size=xx) and new layout (l=6)?

Thanks,
Anshu--
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Convert RAID 5 to RAID 6 while reducing array size

Hi,
I'm trying to convert a 6 device raid5 into a raid6. The 6th device was added into the Raid 5 by mistake instead of a grow operation to convert it into a RAID 6. As such the md device is not being used beyond the size that it had when it was a 5 device raid5.

Can this be done in a single grow step by specifying the reduced size (--array-size=xx) and new layout (l=6)?

Thanks,
Anshu--
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Re: Convert RAID 5 to RAID 6 while reducing array size

On 07/05/2011 20:50, Anshuman Aggarwal wrote:
> Hi,
> I'm trying to convert a 6 device raid5 into a raid6. The 6th device was added into the Raid 5 by mistake instead of a grow operation to convert it into a RAID 6. As such the md device is not being used beyond the size that it had when it was a 5 device raid5.
>
> Can this be done in a single grow step by specifying the reduced size (--array-size=xx) and new layout (l=6)?

Yes it can, with mdadm 3.1.x and a suitably recent kernel. You will need
a backup file on another drive, the same as you did to reshape your
RAID5 from 5 to 6 devices. If you have grown your filesystem, you will
need to shrink it again BEFORE attempting the reshape.

Cheers,

John.

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