Re: Raid5 to another raid level??

[Michael Busby <michael.a.busby@gmail.com>]

Great, will test that in a bit

will mdadm 3.2.2 support converting raid4 to raid5

"A RAID4 can change the number of devices or the size of individual
devices. It cannot be converted to RAID5 yet (though that should be
trivial to implement)"

On 2 September 2011 11:22, NeilBrown <neilb@suse.de> wrote:
> On Fri, 2 Sep 2011 10:12:32 +0100 Michael Busby <michael.a.busby@gmail.com>
> wrote:
>
>> Thanks Neil
>>
>> Is there anyway back from raid0 to raid4 as i know once at raid0 i
>> will no longer be able to add any disks, in theory i could change
>> echo raid0 > /sys/block/md0/md/level,but this would require adding a
>> missing disk to the raid4 at the same time, not sure how easy that
>> would be todo
>>
>
> Yes, you can switch from RAID0 to RAID4 in much the same way as you switch
> from RAID4 to RAID0.
> You can then freeze/add-disk/change-size/unfreeze/wait/switch-back-to-RAID0
> to add more devices.
>
> mdadm-3.2.2 should be able to do all this for you.  i.e. you ask it to --grow
> a RAID and --add some disks at the same time, and it will do all the required
> magic.
>
> This hasn't been tested extensively, but should work in simple cases.
>
> Of course the more devices you have in a RAID0, the less reliability you have
> - but e.g. as a cache for a tape backup system a large RAID0 is fine.
>
> NeilBrown
>
>
>
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