Bug#684708: mdadm: support external metadata arrays correctly

[Dmitrijs Ledkovs]

On 20/08/12 10:42, Michael Tokarev wrote:
> On 13.08.2012 14:10, Miquel van Smoorenburg wrote:
>> Package: mdadm
>> Version: 3.2.5-1
>> Severity: serious
>> Tags: patch wheezy sid
>>
>> The initramfs hook supplied by mdadm doesn't install mdmon. Also, mdmon
>> is not included in the .udeb for the installer.
>>
>> This means that if you have an array with external metadata (ddf or,
>> more widely used, imsm - Intel Matrix Raid) that it will come up
>> readonly. This causes the installer to hang or the system not being
>> able to boot if root is on that array.
>>
>> The attached patch does a couple of things:
>>
>> - it makes sure mdadm is included in the initramfs and the udeb package
>> - it adds a mdadm-waitidle script that runs just before reboot/halt. For all
>>   arrays that are still running, it sets safe_mode_delay to a low version,
>>   sets sync_action to idle, and waits for the array(s) to go idle.
>>   This is needed so that the array is clean, otherwise it will start
>>   to resync at the next boot.
>> - it adds 2 lines of code to mdmon.c so that it symlinks its pidfile
>>   into /run/sendsigs.omit.d - mdmon should not be killed at shutdown,
>>   we still need it after the rootfs has been unmounted.
> 
> There's one more thing missing in there: mdmon should be re-started
> from real root after switching from rootfs -- the takeover.  I guess
> it needs to be added to mdadm-raid.
> 

Why restarted... surely it just can carry-on as it was. Since e.g. /run
doesn't change pre-/post- real-root.


> BTW, why mdadm-waitidle is a separate script?  Can't we fold it into
> mdadm-raid directly?
> 
> The more I think about this all, the more it looks like it is too
> heavily change for wheezy.  I understand the situation, but I still
> think it is not a good idea in general.  Oh well.
> 


-- 
Regards,
Dmitrijs.