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xen-users
Re: [Xen-users] xm migrate headache
Rainer Sokoll a écrit :
> On Tue, Mar 03, 2009 at 06:57:28AM -0700, Nick Couchman wrote:
>
> [drbd in primary/primary]
>
> I was not really correct - there is no filesystem at all in my drbd
> devices:
>
> -------8<-------
> hosta:~ # fdisk -l /dev/drbd4
>
> Disk /dev/drbd4: 2147 MB, 2147381248 bytes
> 255 heads, 63 sectors/track, 261 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
> Disk identifier: 0x000d0023
>
> Device Boot Start End Blocks Id System
> /dev/drbd4p1 1 28 224878+ 82 Linux swap /
> Solaris
> /dev/drbd4p2 29 261 1871572+ 83 Linux
> -------8<-------
>
> The same at hostb.
> So. my drbd devices contain partitions, and these partitions contain a
> filesystem (ext3 and swap, in my case)
>
Maybe this setup falls into the one described in /etc/drbd.conf (from
the "disk" sub-section)?
# In some special circumstances the device mapper stack manages to
# pass BIOs to DRBD that violate the constraints that are set forth
# by DRBD's merge_bvec() function and which have more than one bvec.
# A known example is:
# phys-disk -> DRBD -> LVM -> Xen -> missaligned partition (63) ->
DomU FS
# Then you might see "bio would need to, but cannot, be split:" in
# the Dom0's kernel log.
# The best workaround is to proper align the partition within
# the VM (E.g. start it at sector 1024). (Costs 480 KiByte of storage)
# Unfortunately the default of most Linux partitioning tools is
# to start the first partition at an odd number (63). Therefore
# most distribution's install helpers for virtual linux machines will
# end up with missaligned partitions.
# The second best workaround is to limit DRBD's max bvecs per BIO
# (= max-bio-bvecs) to 1. (Costs performance).
# max-bio-bvecs 1;
Maybe you could try with the option "max-bio-bvecs 1;" as described...
--
Maxim Doucet (maxim@xxxxxxxxxxxx)
sys engineer @ la maison
+33 (0)1 41 12 2000
www.alamaison.fr
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