Re: [Xen-users] gluserfs?

[Joseph Glanville <joseph.glanville@xxxxxxxxxxxxxx>]

Hi,

I would highly recommend AGAINST trying to run Xen DomUs on GlusterFS.
Firstly it is a file-system, you should really avoid running any production virtual machines backing to a file - it is a world of pain you really don't want to deal with.
Secondly GlusterFS just isn't fit for a production workload of this type at this time, this isn't so much a jab at GlusterFS as it is using a screwdriver when you need a hammer.
GlusterFS is suited to large sequential file accesses, not completely random IOPs intensive loads like virtual machines.
I have ran VMs on it to my own detriment and I will never do so again. I encountered many strange issues especially when I started to mix striping with replication over large numbers of servers to try achieve good random IO performance.
In my experience this is a road many have tried to walk but have all walked away from scarred in some shape or form.

If you really need a clustered solution there are approaches using Luster VFS etc but the problem is that distributed storage solutions that are production quality for running VMs are closely guarded secrets.

Your best bet for stability and ease of testing etc is DRBD replicated iSCSI - not fancy but highly effective and will push the IOPs you need for good VM performance if you invest in a few SSDs and a decent RAID controller.

Joseph.

On 3 November 2011 12:23, Miles Fidelman <mfidelman@xxxxxxxxxxxxxxxx> wrote:

Florian,

Florian Heigl wrote:

2011/11/2 Miles Fidelman<mfidelman@meetinghouse.net>:

Anybody running Xen on top of GlusterFS (or tried with a recent version)?
 How well does it work?

I tried around 7 months ago.
The O_DIRECT problem did not go away, domUs would boot, but hang at mountroot.

can you elaborate just a bit?

and... do you remember which version of Gluster you were experimenting with?

Documentation was contradictive, but back then they had just hired a
professional tech writer to clean up things.

I would recommend you give it a try, but I would also recommend you to
not keep trying and trying like I had.

Right.  Thanks :-)

Miles

--
In theory, there is no difference between theory and practice.
In<fnord>  practice, there is.   .... Yogi Berra

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