Bug#614353: multipath-tools-boot: upgrade to squeeze breaks machines with root on iscsi

[Hanspeter Kunz]

On Mon, 2011-02-28 at 14:34 +0100, Hanspeter Kunz wrote:
> On Mon, 2011-02-28 at 03:07 +0530, Ritesh Raj Sarraf wrote:
> > On 02/27/2011 04:26 PM, Hanspeter Kunz wrote:
> > > ok, let me restate the issue, it is actually quite simple:
> > > 
> > > During boot, after multipath assembled its devices, I see
> > > the /dev/mapper multipath devices (which is fine) but
> > > the /dev/disk/by-uuid symlinks point to one of the underlying iscsi
> > > devices. Therefore, I cannot not boot using root=/dev/disk/by-uuid/...
> > > because this leads to an error (as the device is already used by
> > > multipath).
> > > 
> > > when I boot the same system using root=/dev/mapper/... it works. 
> > > 
> > > after booting, when the system is up, the /dev/disk/by-uuid symlinks
> > > point to the multipath devices (an not anymore to the iscsi devices
> > > directly), which is how it should be.
> > > 
> > > so the only thing that is missing is that these symlinks are created
> > > correctly during boot.
> > > 
> > 
> > Okay!! I'll look into it soon as time permits. In case you get a root
> > cause, please do share.
> 
> cool, thanks!
> 
> I tried to nail down the problem a bit more:
> 
> 1. booted the system with break=mountroot
> 2. manually executed /scripts/local-top/iscsi. I get the two iscsi
> devices /dev/sda and /dev/sdb (plus all the partitions) as expected.
> I /dev/disk/by-uuid there are symlinks to the /dev/sdbx partitions. So
> far everything is as expected.
> 3. I manually removed the symlinks in /dev/disk/by-uuid (although this
> is probably not necessry).
> 4. manually executed /scripts/local-top/multipath. This re-creates the
> same symlinks in /dev/disk/by-uuid, again pointing to the /dev/sdbx
> partitions, instead of pointing to the /dev/dm-x partitions

If I do the above steps on a lenny system (with otherwise identical
configuration) I get the same results except that after step 4
the /dev/disk/by/uuid symlinks point to the /dev/dm-x devices (as it
should be).

If I boot the squeeze system (by using the root=/dev/mapper/... instead
of root=/dev/disk/by-uuid/...) I see that also after booting
the /dev/disk/by-uuid symlinks point to the /dev/sdbx devices (in
contrast to what I said in my previous email). So at least the behavior
during boot and after it is consistent :)

Thus, my guess is, that it is the udev rules (dm, persistent-storage-dm)
which then actually would be a bug in dmsetup.

But unfortunately I do not understand much about udev rules. If you
would like me to test anything, let me know.

cheers,
Hp