[Openstack-operators] Shared storage HA question

Joe Topjian joe.topjian at cybera.ca
Wed Jul 24 19:08:30 UTC 2013

Hi Jacob,

Are you using SAS or SSD drives for Gluster? Also, do you have one large
Gluster volume across your entire cloud or is it broke up into a few
different ones? I've wondered if there's a benefit to doing the latter so
distribution activity is isolated to only a few nodes. The downside to
that, of course, is you're limited to what compute nodes instances can
migrate to.

I use Gluster for instance storage in all of my "controlled" environments
like internal and sandbox clouds, but I'm hesitant to introduce it into
production environments as I've seen the same issues that Razique describes
-- especially with Windows instances. My guess is due to how NTFS writes to

I'm curious if you could report the results of the following test: in a
Windows instance running on Gluster, copy a 3-4gb file to it from the local
network so it comes in at a very high speed. When I do this, the first few
gigs come in very fast, but then slows to a crawl and the Gluster processes
on all nodes spike.


On Wed, Jul 24, 2013 at 12:37 PM, Jacob Godin <jacobgodin at gmail.com> wrote:

> Oh really, you've done away with Gluster all together? The fast backbone
> is definitely needed, but I would think that was the case with any
> distributed filesystem.
> MooseFS looks promising, but apparently it has a few reliability problems.
> On Wed, Jul 24, 2013 at 3:31 PM, Razique Mahroua <
> razique.mahroua at gmail.com> wrote:
>> :-)
>> Actually I had to remove all my instances running on it (especially the
>> windows ones), yah unfortunately my network backbone wasn't fast enough to
>> support the load induced by GFS - especially the numerous operations
>> performed by the self-healing agents :(
>> I'm currently considering MooseFS, it has the advantage to have a pretty
>> long list of companies using it in production
>> take care
>> Le 24 juil. 2013 à 16:40, Jacob Godin <jacobgodin at gmail.com> a écrit :
>> A few things I found were key for I/O performance:
>>    1. Make sure your network can sustain the traffic. We are using a 10G
>>    backbone with 2 bonded interfaces per node.
>>    2. Use high speed drives. SATA will not cut it.
>>    3. Look into tuning settings. Razique, thanks for sending these along
>>    to me a little while back. A couple that I found were useful:
>>       - KVM cache=writeback (a little risky, but WAY faster)
>>       - Gluster write-behind-window-size (set to 4MB in our setup)
>>       - Gluster cache-size (ideal values in our setup were 96MB-128MB)
>> Hope that helps!
>> On Wed, Jul 24, 2013 at 11:32 AM, Razique Mahroua <
>> razique.mahroua at gmail.com> wrote:
>>> I had much performance issues myself with Windows instances, and I/O
>>> demanding instances. Make sure it fits your env. first before deploying it
>>> in production
>>> Regards,
>>> Razique
>>> *Razique Mahroua** - **Nuage & Co*
>>> razique.mahroua at gmail.com
>>> Tel : +33 9 72 37 94 15
>>> <NUAGECO-LOGO-Fblan_petit.jpg>
>>> Le 24 juil. 2013 à 16:25, Jacob Godin <jacobgodin at gmail.com> a écrit :
>>> Hi Denis,
>>> I would take a look into GlusterFS with a distributed, replicated
>>> volume. We have been using it for several months now, and it has been
>>> stable. Nova will need to have the volume mounted to its instances
>>> directory (default /var/lib/nova/instances), and Cinder has direct support
>>> for Gluster as of Grizzly I believe.
>>> On Wed, Jul 24, 2013 at 11:11 AM, Denis Loshakov <dloshakov at gmail.com>wrote:
>>>> Hi all,
>>>> I have issue with creating shared storage for Openstack. Main idea is
>>>> to create 100% redundant shared storage from two servers (kind of network
>>>> RAID from two servers).
>>>> I have two identical servers with many disks inside. What solution can
>>>> any one provide for such schema? I need shared storage for running VMs (so
>>>> live migration can work) and also for cinder-volumes.
>>>> One solution is to install Linux on both servers and use DRBD + OCFS2,
>>>> any comments on this?
>>>> Also I heard about Quadstor software and it can create network RAID and
>>>> present it via iSCSI.
>>>> Thanks.
>>>> P.S. Glance uses swift and is setuped on another servers
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Joe Topjian
Systems Architect
Cybera Inc.


Cybera is a not-for-profit organization that works to spur and support
innovation, for the economic benefit of Alberta, through the use
of cyberinfrastructure.
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