[Lustre-discuss] VMWare or VirtualBox..

[Andreas Dilger]

On Aug 17, 2008  09:08 -0500, Troy Benjegerdes wrote:
> There seem to be a couple of assumptions here that would be worth
> examining further.
> 
> My first thought is that running Lustre under something like Xen might
> be very usefull for virtualization, failover, and load balancing.
> 
> If there is some potential resource deadlock that could occur, there ought
> to be some diagram or documentation of what deadlocks are possible. It
> would be a lot of work to conclusively figure out what the potential
> deadlocks actually are.. But it seems like a worthwhile excercise, and
> running Lustre in a VM would be a good way to do QA testing so that new
> deadlocks are not added by code changes.

If you are talking about running Lustre clients to host a distributed
filesystem for many VMs then I think that is reasonable.  Running
many VMs on the same system, both client and server is quite pointless -
you may as well just use a local filesystem or similar.

There is definitely a known deadlock with a client and OST on the same
node, when the client is trying to free memory, writes dirty data to
Lustre, and then the local OST needs to allocate something to complete
the IO where the VM blocks waiting for the client to write out its data...
I don't know if this would happen with two VMs however.

> On Fri, Aug 15, 2008 at 03:17:39PM -0700, Klaus Steden wrote:
> > You're likely to find that performance will suffer when run under a VM.
> > Lustre makes pretty extensive use of all the resources at its disposal, and
> > having to compete with physical devices under a VM that runs as an ordinary
> > user process is more than likely going to lead to resource deadlocks.
> > 
> > I wouldn't suggest running Lustre under VMs.

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.