[gpfsug-discuss] Reexporting GPFS via NFS on VM host

Dean Hildebrand dhildeb at us.ibm.com
Fri Aug 14 18:54:59 BST 2015

Thanks for the replies Simon...

Chris, are you using -v to give the container access to the nfs subdir (and
hence to a gpfs subdir) (and hence achieve a level of multi-tenancy)?  Even
without containers, I wonder if this could allow users to run their own VMs
as root as well...and preventing them from becoming root on gpfs...

I'd love for you to share your experience (mgmt and perf) with this
architecture once you get it up and running.  Some side benefits of this
architecture that we have been thinking about as well  is that it allows
both the containers and VMs to be somewhat ephemeral, while the gpfs
continues to run in the hypervisor...

To ensure VMotion works relatively smoothly, just ensure each VM is given a
hostname to mount that always routes back to the localhost nfs server on
each machine...and I think things should work relatively smoothly.  Note
you'll need to maintain the same set of nfs exports across the entire
cluster as well, so taht when a VM moves to another machine it immediately
has an available export to mount.

Dean Hildebrand
IBM Almaden Research Center

From:	"Simon Thompson (Research Computing - IT Services)"
            <S.J.Thompson at bham.ac.uk>
To:	gpfsug main discussion list <gpfsug-discuss at gpfsug.org>
Date:	08/13/2015 07:33 AM
Subject:	Re: [gpfsug-discuss] Reexporting GPFS via NFS on VM host
Sent by:	gpfsug-discuss-bounces at gpfsug.org

>I've set up a couple of VM hosts to export some of its GPFS filesystem
>via NFS to machines on that VM host[1,2].

Provided all your sockets no the VM host are licensed.

>Is live migration of VMs likely to work?
>Live migration isn't a hard requirement, but if it will work, it could
>make our life easier.

Live migration using a GPFS file-system on the hypervisor node should work
(subject to the usual caveats of live migration).

Whether live migration and your VM instances would still be able to NFS
mount (assuming loopback address?) if they moved to a different
hypervisor, pass, you might get weird NFS locks. And if they are still
mounting from the original VM host, then you are not doing what the FAQ
says you can do.


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