Bug#737132: Regression: wheezy initrd loads md raids only if defined on mdadm.conf even with INITRDSTART='all'

[Fabio Fantoni]

Il 30/01/2014 16:15, Michael Tokarev ha scritto:
> 30.01.2014 17:45, Fabio Fantoni wrote:
>> Package: mdadm
>> Version: 3.2.5-5
>> Severity: normal
>>
>> I'm attempting to restore a backup of a root partition on a set of brand new disks (md raid1).
>> On Wheezy, initramfs doesn't show md devices if they are not defined in /etc/mdadm/mdadm.conf even if on /etc/default/mdadm there is INITRDSTART='all'.
>> Such problem may be caused by a regression (squeezy or wheezy) because on lenny I've been always did such task without problem.
> []
>> Personalities : [raid1]
>> md1 : active raid1 sda3[0] sdb3[1]
>>        72610624 blocks super 1.2 [2/2] [UU]
> With 1.x superblock, the term "all" actually refers to all arrays belonging to this host,
> which has current hostname recorded in the superblock (1.x format superblock has a place
> for "homehost" field, while 0.90 format didn't have this field).
>
> Previously, mdadm really tried to assemble any arrays found, but this turned out to be
> wrong.  For example, when you insert hard drives from another system for recovery of
> broken raid/filesystem, mdadm should NOT assemble arrays from there by default, because
> this way we've a high risk of breaking stuff further.
>
> Please ensure that you have the right homehost in your raid arrays (mdadm -D will tell you),
> and -- the second part of the picture -- that this hostname is set correctly inside initrd
> when mdadm is run.
>
> Please note also that modern mdadm will try to check homehost even for 0.90 superblocks,
> by doing some magic with the array UUID.  If your arrays were created by sufficiently
> recent mdadm, the UUID has some bits of homehost mixed in.
>
> Thanks,
>
> /mjt

Thanks for reply.
The new md arrays were created by Wheezy persistent install on usb 
pendrive used as recovery system/tools.
The root of system to recover is also Wheezy.
Than the arrays are created with 1.2 superblock and different hostname.
Is it possible to force the hostname on mdadm create?
If so, is the UUID going to work too?
Otherwise if it is possible to change it only with --update, will the 
UUID contain the old hostname and will it be a problem on initrd start?