[Gluster-users] how well will this work

Miles Fidelman mfidelman at meetinghouse.net
Thu Dec 27 23:00:18 UTC 2012

Ok... now that's diametrically the opposite response from Dan Cyr's of a 
few minutes ago.

Can you say just a bit more about your configuration - how many nodes, 
do you have storage and processing combined or separated, how do you 
have your drives partitioned, and so forth?



Joe Julian wrote:
> Trying to return to the actual question, the way I handle those is to 
> mount gluster volumes that host the data for those tasks from within 
> the vm. I've done that successfully since 2.0 with all of those services.
> The limitations that others are expressing have as much to do with 
> limitations placed on their own designs as with their hardware. Sure, 
> there are other less stable and/or scalable systems that are faster, 
> but with proper engineering you should be able to build a system that 
> meets those design requirements.
> The one piece that wasn't there before but now is in 3.3 is the 
> "locking and performance problems during disk rebuilds" which is now 
> done at a much more granular level and I have successfully self-healed 
> several vm images simultaneously while doing it on all of them without 
> any measurable delays.
> Miles Fidelman <mfidelman at meetinghouse.net> wrote:
>     Joe Julian wrote:
>         It would probably be better to ask this with end-goal
>         questions instead of with a unspecified "critical feature"
>         list and "performance problems".
>     Ok... I'm running a 2-node cluster that's essentially a mini cloud stack
>     - with storage and processing combined on the same boxes.  I'm running a
>     production VM that hosts a mail server, list server, web server, and
>     database; another production VM providing a backup server for the
>     cluster and for a bunch of desktop machines; and several VMs used for a
>     variety of development and testing purposes. It's all backed by a
>     storage stack consisting of linux raid10 -> lvm -> drbd, and uses
>     pacemaker for high-availability failover of the
>     production VMs.  It all
>     performs reasonably well under moderate load (mail flows, web servers
>     respond, database transactions complete, without notable user-level
>     delays; queues don't back up; cpu and io loads stay within reasonable
>     bounds).
>     The goals are to:
>     - add storage and processing capacity by adding two more nodes - each
>     consisting of several CPU cores and 4 disks each
>     - maintain the flexibility to create/delete/migrate/failover virtual
>     machines - across 4 nodes instead of 2
>     - avoid having to play games with pairwise DRBD configurations by moving
>     to a clustered filesystem
>     - in essence, I'm looking to do what Sheepdog purports to do, except in
>     a Xen environment
>     Earlier versions of gluster had reported problems with:
>     - supporting databases
>     - supporting VMs
>     - locking and performance problems during disk rebuilds
>     - and... most of the gluster documentation implies that it's
>     preferable
>     to separate storage nodes from processing nodes
>     It looks like Gluster 3.2 and 3.3 have addressed some of these issues,
>     and I'm trying to get a general read on whether it's worth putting in
>     the effort of moving forward with some experimentation, or whether this
>     is a non-starter.  Is there anyone out there who's tried to run this
>     kind of mini-cloud with gluster?  What kind of results have you had?
>         On 12/26/2012 08:24 PM, Miles Fidelman wrote:
>             Hi Folks, I find myself trying to expand a 2-node
>             high-availability cluster from to a 4-node cluster. I'm
>             running Xen virtualization, and currently using DRBD to
>             mirror data, and pacemaker to failover cleanly. The thing
>             is, I'm trying to add 2 nodes to the cluster, and DRBD
>             doesn't scale. Also, as a function of rackspace limits,
>             and the hardware at hand, I can't separate storage nodes
>             from compute nodes - instead, I have to live with 4 nodes,
>             each with 4 large drives (but also w/ 4 gigE ports per
>             server). The obvious thought is to use Gluster to assemble
>             all the drives into one large storage pool, with
>             replication. But.. last time I looked at this (6 months or
>             so back), it looked like some of the critical features
>             were brand new, and performance seemed to be a problem in
>             the configuration I'm thinking of. Which leads me to my
>             question: Has the situation improved to the point that I
>             can use Gluster this way? Thanks very much, Miles Fidelman
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In theory, there is no difference between theory and practice.
In practice, there is.   .... Yogi Berra

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