Re: [Xen-users] Domain-0 freezes when mounting a cloned domU with dd

[Franck ELIE <Franck.Elie@xxxxxxxxxxxxxxx>]

Franck ELIE a écrit :
> Hi
>
> When cloning à domU with 'dd' command (after a domU shutdown), it 
> seems to be very important to perform a 'fsck' on cloned partitions 
> before to mount because if we don't, it freezes Domain-0 and next dom-U.
> Just before the kernel froze, logs are full of such message :
> kernel: 
> >>ext3_orp>ext3_orph>ext3_orph>ext3_orph>ext3_orpha>ext3_orp>ext3_orpha>ext3_or>ext3_or>ext3_orph>e 
>
> xt3_orp>ext3_orp>ext3_orph>ext3_or>ext3_orpha>ext3_or>ext3_orp>ext3_or>ext3_orp>ext3_orph>ext3_orpha>ext3_or>ext3_orp>ext3_orp>ext3_ 
> or>ext3_orphan>ext3_orphan_>ext3_orpha>ext3_orp>ext3_orp>ext3_orph>ext3_orphan>ext3_orp>ext3_orp>ext3_orph> 
> ....
> Note that when performing a fdisk on such partitions I obtain this 
> output :
> # fsck.ext3 /dev/mapper/CMS1
> e2fsck 1.40-WIP (14-Nov-2006)
> /dev/mapper/CMS1: recovering journal
> Truncating orphaned inode 32474 (uid=101, gid=104, mode=0140777, size=0)
> /dev/mapper/CMS1: clean, 37928/221312 files, 250275/441779 blocks
>
> By the way, fsck on the template domU seems to be OK.
>
> So, here are my questions :
> - Do you know why is it necessary to perform fsck ? Should I use 
> specific options with dd to avoid this effect on the cloned FS ?
> - Concerning the kernel freeze (that seems not to be specific to my 
> distrib or xen),  is it a kernel bug ?
> Regards
>
>  Franck
>
> P.S.: xen 3.03, kernel 2.6.18-4-xen-686, Debian Etch, 1 domU per LUN 
> of 2Go, no LVM
Here are the result of tests I just performed to understand what 's wrong :
- there is a MD5 difference between the sum computed from LUN of the 
domU storage and the image file generated with 'dd' WHEN the backup is 
performed just after the domU shutdown (less than 3min).
- domain-0 have enough memory (8Go) to copy the domU (2Go)

So, my FS trouble would to be related with a partial copy of domU that 
seems to be performed with 'dd' before before the end of the memory 
flush away to disk domU.
So do you know how to perform the memory flush related to a domU in 
order to backup the disk correctly ?
Any suggestion would be appreciate

Regards

 Franck



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