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

[Jérémie Tarot]

Hi,

This is a very interesting scenario...

2011/5/23 MORITA Kazutaka <morita.kazutaka at lab.ntt.co.jp>

> 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.
>

In this given setup:
   * Can we export the same sheepdog volume from many/all sheepdog cluster
members at the same time ?
   * Can't we use multipathing to connect to the targets to gain fault
tolerance ?

Thanks
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