[Sheepdog] how can i mount linux host on Sheepdog device?

[MORITA Kazutaka]

At Sun, 22 May 2011 11:25:44 +0200,
Gandalf Corvotempesta wrote:
> 2011/5/21 MORITA Kazutaka <morita.kazutaka at lab.ntt.co.jp>
> >
> > The patched version is also available at:
> >  git://sheepdog.git.sourceforge.net/gitroot/sheepdog/qemu iscsi
> >
> > See also
> > https://sourceforge.net/apps/trac/sheepdog/wiki/General%20Protocol%20Support
> 
> 
> If I understand correctly with this patch i'll be able to export a whole
> sheepdog cluster in a single iSCSI block device and then mount it on a
> different server that will run the VMs ?
> Like a distributed SAN, for example:

You can export a Sheepdog volume (not a whole sheepdog cluster) as an
ISCSI LUN.  Please note that the iSCSI support is experimental.  I/O
is not asynchronous (poor performance), and the export configuration
is not shared among Sheepdog nodes.

> 
> 3 sheepdog node merged in a single cluster and then exported to a single
> iSCSI device.
> In front of them, will be 5 debian boxes that mounts the iSCSI device and
> run VM from it ?
> 
> If one debian box will die, other 4 will take care of the lost VM by running
> them from the iSCSI devices archieving fault tollerance.

Automatic failover of VMs is not supported.  I think it is out of
scope of the storage system.

> 
> If one sheepdog node will die, other sheepdog will takeover it and move the
> iSCSI target to an available node?

No.  You need to start the iSCSI target on the available node, and
export Sheepdog volumes with the same configuration manually.


Thanks,

Kazutaka