[rear-users] REAR restore on multipath

Gratien D'haese gratien.dhaese at it3.be
Mon Feb 18 10:22:09 CET 2013



Hi, 

It would be nice if you could create an issue tracker for this
interesting problem. 

I see 3 potential problems so far:
1/ by using
friendly names is not a guarantee that the the same SAN-device names are
used after the reboot. It is better to use the by-id paths. I wouldn't rely
on friendly names or aliases in recovery mode
2/ did you recreate the
initrd with mkinitrd?
3/ did you add the multipathd and boot.multipath
services at boot time? 

regards, Gratien 

On Sun, 17 Feb 2013 21:07:36
+0100, reynald CHEKHINA  wrote:  

Hello, 

I have add multipath to boot
iso, load module dm_multipath create multipath with multipath -v3 and see
mpath0. A launch rear recover and change disklayout.conf file with mpath0,
mpath0p1 .... creation and restoration works well. After i change root to
/mnt/local i modify /etc/multipath.conf, /etc/fstab,
/var/lib/multipath/bindings, /etc/lvm/lvm.conf and
/etc/sysconfig/mkinitrd/multipath. I recreate grub to map on /
dev/mapper/mpath0 recreate initrd .
 I reboot the server but i have a
kernel panic message : 

mount: could not find filesystem '/dev/root'

setuproot: moving /dev failed: No such file or directory
 setuproot: error
mounting /proc: No such file or directory
 setuproot: error mounting /sys:
No such file or directory
 switchroot: mount failed: No such file or
directory
 Kernel panic - not syncing: Attempted to kill init! 

Can you
help me please ?  
On Thu, 14 Feb 2013 16:48:16 +0100 (CET), Dag Wieers
wrote:
> On Thu, 14 Feb 2013, reynald CHEKHINA wrote:
> 
>> I migrate
physical machine RHEL5.4 with local disk to other physical
>> machine with
boot on san. When I try to restore I see only /dev/sda-d of
>> 4 path lun
and don't see mpath.
>> It's possible to restore on mulitpath /dev/mpath
?
> 
> Since the original system does not use multipathing itself, the
rescue 
> image does not have it included. And it's even possible that the
original 
> system doesn't have multipath tools installed at all.
> 
> What
you currently can do to work around this is:
> 
> - Include the multipath
tools manually in the configuration
> - Create an additional script that
starts multipathd during rescue boot
> 
> But we could discuss how we want
to do this in the future. In this case we 
> could always include
multipathd if it is on the original system, and run 
> it on rescue boot.
It can be useful, and is harmless (?) if there's no 
> multipathing.
> 
>
Same for backup methods, having other tools included (e.g. rsync, ...) 
>
when installed, gives more options during restore.
> 

I'm sure he will end
at issue https://github.com/rear/rear/issues/183 [1]
Our code is not 100%
ready yet for migrating to SAN-only disks. Need some time to continue work
on this. Unfortunately, time is not my best friend these days
;-(

Gratien

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-- 
Gratien
D'haese
IT3 Consultants bvba 
Vennestraat 15, B-2560 Nijlen



Links:
------
[1] https://github.com/rear/rear/issues/183
[2]
mailto:rear-users at lists.relax-and-recover.org
[3]
http://pikachu.3ti.be/mailman/listinfo/rear-users
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