[Gluster-users] how well will this work

Joe Julian joe at julianfamily.org
Thu Dec 27 22:23:42 UTC 2012


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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