Re: Multiple arrays out of devices belonging to single array

[NeilBrown <neilb@suse.de>]

[-- Attachment #1: Type: text/plain, Size: 1296 bytes --]

On Fri, 05 Dec 2014 12:27:31 +0300 Michael Tokarev <mjt@tls.msk.ru> wrote:

> Hello.
> 
> We in Debian have 2 rather similar bugreports which are somewhat old:
>  http://bugs.debian.org/599352
>  http://bugs.debian.org/694513
> Last bugreport is against mdadm-3.2.5, so not THAT old.
> 
> Basically, it smells like there's a possibility for mdadm to assemble
> more than one (degraded) array out of components of the same array.
> 
> So I wonder if mdadm or kernel have some protection of this situation
> from happening.  Something like looking at already active/assembled
> devices to see if the same UUID is already used before trying to
> assemble another array.
> 
> It might be better done in kernel because this way the process might
> be freee from races when two mdadm instances tries to do the work in
> parallel.
> 
> Are these bugs for real?

Certainly are.
Fix in 3.3 I think.

commit 0431869cec4c673309d9aa30a2df4b778bc0bd24
Author: NeilBrown <neilb@suse.de>
Date:   Wed Oct 10 18:27:32 2012 +1100

    Fix up interactions between --assemble and --incremental

is one part of the fix.  I cannot quickly find another patch which obviously
relates to the symptoms described, but my vague memories suggest there was
more than one patch.

NeilBrown

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 811 bytes --]