is it possible to change the UUID of an array?

is it possible to change the UUID of an array?

[Adam Nevins]

Hi,

I had a RAID-1 with two mirrors as my root partition.  I decided to
fail/remove one of the mirrors prior to upgrading parts of the OS so
that I'd have a backup just in case things went horribly wrong.  After
doing the upgrade, I wanted to compare the two mirrors, so I assembled a
new md with the failed mirror.  So far, so good.

The problem is that I now have two arrays with the same UUID.  I'm
assuming that automatic assembly is now broken.  For now, I've changed
mdadm.conf to specify the physical devices, but what I'd like to do is
generate a new UUID for one of the mirrors.  I haven't found a way to do
this without recreating the array.

kernel version: 2.6.11
mdadm version:  1.12.0

Thanks in advance,

Adam
-- 
Adam Nevins <univac@comcast.net>

Re: is it possible to change the UUID of an array?

[Neil Brown]

On Friday December 2, univac@comcast.net wrote:
> Hi,
> 
> I had a RAID-1 with two mirrors as my root partition.  I decided to
> fail/remove one of the mirrors prior to upgrading parts of the OS so
> that I'd have a backup just in case things went horribly wrong.  After
> doing the upgrade, I wanted to compare the two mirrors, so I assembled a
> new md with the failed mirror.  So far, so good.
> 
> The problem is that I now have two arrays with the same UUID.  I'm
> assuming that automatic assembly is now broken.  For now, I've changed
> mdadm.conf to specify the physical devices, but what I'd like to do is
> generate a new UUID for one of the mirrors.  I haven't found a way to do
> this without recreating the array.

Not easily, no.  Maybe I could add an
  --update=uuid:1234:5678.....
for mdadm-2.2 ....

NeilBrown