Re: [Xen-users] RE: Tutorial : Debian, Xen and CLUSTER / GFS Support

[Michael Mey <michael.mey@xxxxxx>]

On Tuesday 22 November 2005 18:30, PAINCHAUD Christophe wrote:
> >Hey, nice tutorial :)
>
> Thank you ;)
>
> >Have you got domUs running with image-files on a gfs?
>
>       I tried to put some domUs images on a GFS shared (through GNBD)
> filesystem. Everything was running fine until I launched the domU : I had
> tons of I/O errors. On CLUSTER ML, many users are reporting the same
> problem when they are trying to lock and read/write on a very large file
> (over 1Gb).
I set up a RedHat Cluster on two Debian dom0s running xen-devel (changeset 
from last week) and I made the same experience. I also got a lot of I/O 
errors within a domU once starting it with vbd as image file stored on gfs.

Thanks to Sylvain Coutant, now we know what is the problem with that scenario 
(because I also thought I did something the wrong way).
Btw, just for completion, my syslog said the following when I started a domU 
on gfs:

Nov 15 17:37:27 testpc-022 logger: /etc/xen/scripts/block: Writing 
backend/vbd/13/770/hotplug-status connected to xenstore.
Nov 15 17:37:27 testpc-022 logger: /etc/xen/scripts/block: Writing 
backend/vbd/13/769/hotplug-status connected to xenstore.
Nov 15 17:37:28 testpc-022 kernel: GFS: fsid=xencl:xen3-root.0: warning: 
assertion "gfs_glock_is_locked_by_me(ip->i_gl)" failed
Nov 15 17:37:28 testpc-022 kernel: GFS: fsid=xencl:xen3-root.0:   function = 
gfs_prepare_write
Nov 15 17:37:28 testpc-022 kernel: GFS: fsid=xencl:xen3-root.0:   file 
= /usr/local/src/cluster-1.01.00/gfs-kernel/src/gfs/ops_address.c, line = 329
Nov 15 17:37:28 testpc-022 kernel: GFS: fsid=xencl:xen3-root.0:   time = 
1132072648

Something's seems to go wrong with the locking mechanism of gfs ( I used 
lock_dlm for distributed locking).

Since I'm evaluating different ways of storing domUs' vbds for migration, I'll 
go on and test some more stuff with FC and iSCSI.

Cheers,

Michael

-- 
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Michael Mey                                  
Thinking Objects Software GmbH    |   mailto: michael.mey@xxxxxx 
Lilienthalstrasse 2/1                         |   phone: +49 711 88770-147
70825 Stuttgart-Korntal, Germany  |   fax: +49 711 88770-449
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