Re: status of raid 4/5 disk reduce

[Alex Lilley <alex@redwax.co.uk>]

Hi Michael

I posed this a few weeks back but haven't seen any activity on it yet or 
any suggestion as to when this might be possible.

For reference, my thread started here: 
http://marc.info/?l=linux-raid&m=122753511309332&w=2

Cross fingers for this because I think it is a real killer feature.

Regards

Alex

Michael Brancato wrote:
> I'm curious as to the status of the ability to reduce the number of 
> disks in a RAID 4/5 array.  I would like the ability to reshape a 4 
> disk raid4/5 to a 3 disk raid4/5 for flexibility.
>
> here is what I want to do....
> $ sudo mdadm /dev/md0 --fail /dev/disk4 --remove /dev/disk4
> mdadm: set /dev/disk4 faulty in /dev/md0
> mdadm: hot removed /dev/disk4
> $ sudo mdadm --grow /dev/md0 -n3
> mdadm: /dev/md0: Cannot reduce number of data disks (yet).
>
> I know this capability is missing in the md driver.  What is needed to 
> make it work and is anyone currently working on it?
>
> Regards,
>