[Gluster-users] Gluster v 3.3 with KVM and High Availability

Fernando Frediani (Qube) fernando.frediani at qubenet.net
Thu Jul 12 08:59:10 UTC 2012

Gluster is not ready to run Virtual Machines at all. Yes you can build a 2 node cluster and live migrate machines, but the performance is poor and they need to do a lot of work on it yet.
I wouldn't put in production even a cluster with low performance web server VMs until this is solved. For Archive or Multimedia general storage maybe, but not to run VMs.
Perhaps someone is intending to integrate with RHEV (seems they are as it's going to be on oVirt 3.1 now) so they will put more effort to solve this problem that 10 of 10 of those who tested  are reporting the same thing.


-----Original Message-----
From: gluster-users-bounces at gluster.org [mailto:gluster-users-bounces at gluster.org] On Behalf Of Mark Nipper
Sent: 12 July 2012 09:40
To: Brian Candler
Cc: gluster-users at gluster.org
Subject: Re: [Gluster-users] Gluster v 3.3 with KVM and High Availability

On 12 Jul 2012, Brian Candler wrote:
> And I forgot to add: since a KVM VM is a userland process anyway, I'd 
> expect a big performance gain when KVM gets the ability to talk to 
> libglusterfs to send its disk I/O directly, without going through a 
> kernel mount (and hence bypassing the kernel cache). It looks like this is being developed now:
> http://lists.gnu.org/archive/html/qemu-devel/2012-06/msg01745.html
> You can see the performance figures at the bottom of that post.

	Something concerns me about those performance figures.
If I'm reading them correctly, the normal fuse mount performance is about what I was seeing, 2-3MB.  And now bypassing everything, libglusterfs is still capping out a little under 20MB/s.

	So am I kidding myself that approaching 45-50MB/s with a FUSE based Gluster mount and using cache=writethrough is actually a safe thing to do really?  I know the performance is abysmal without setting the cache mode, but is using writethrough really safe, or is it a recipe for disaster waiting to happen?

Mark Nipper
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+1 979 575 3193
I cannot tolerate intolerant people.
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