[Lustre-discuss] VMWare or VirtualBox..

[Andreas Dilger]

On 2010-05-26, at 02:14, arunas.bruozis at bt.com wrote:
> I’m an IT administrator and have recently started playing w/ lustre and was wondering if there’s any way it could play with VMWare ESX as shared/distributed storage.
> I saw your posting from ’08 (http://www.mail-archive.com/lustre-discuss@lists.lustre.org/msg01975.html) related to lustre/VMWare, so I was wondering if you had ever received any feedback or even implemented a solution where lustre & VMWare ESX/4.0 ?
> Greatly appreciate any feedback/suggestions that you might have on the topic.

I don't really use VMs very much, but in theory it is just doing regular file IO to the filesystem image, so running a VM on top of Lustre is no problem at all.  I'm not sure what the IO pattern from the VM would look like, but I also assume that there is never more than a single VM with write access to the same image file, even if the VM is doing some sort of COW with a per-VM write delta file and a read-only full image.  That will still play nicely with Lustre because it can have proper shared read access to the full image, and clients will get full-file write locks on their COW files and there will not be contention.

If your question is about mounting Lustre clients WITHIN a VM to get shared filesystem access, then I have no idea how it will behave.  In theory it is possible, but it may "hog" too much of the RAM because it will make assumptions on cache sizes and other tunables based on the total RAM size.

The third option (I don't know which one you are looking at) is to run Lustre servers within the VM, which I would recommend against.  This will introduce significant performance issues, and given that Lustre is targeted at "larger than a single server" installations, it doesn't make sense to use Lustre and then give it only a small fraction of the resources of a system.  You would be better off to reduce the number of OSTs and just give them the whole server.

Cheers, Andreas
--
Andreas Dilger
Lustre Technical Lead
Oracle Corporation Canada Inc.