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Re: DRBD storage for Openstack installations


Hi Oleg,

thank you very much for your post, it's really didactic. We are taking a
different approach for HA at storage level, but I have worked formerly with
DRBD and I think it's a very good choice.

I'm curious about how you have deployed nova-volume nodes in your
architecture. You don't specify if the two nodes of the DRBD cluster run one
or two instances of nova-volume. If you run one instance probably you have
implemented some kind of fault-tolerant active-passive service if the
nova-volume process fails in the active node, but I would like to know if
you can run an active-active two nova-volume instances on two different
physical nodes on top of the DRBD shared resource.


Diego Parrilla
*www.stackops.com | * diego.parrilla@xxxxxxxxxxxx** | +34 649 94 43 29 |
* <http://www.stackops.com>

On Thu, May 26, 2011 at 1:29 PM, Oleg Gelbukh <ogelbukh@xxxxxxxxxxxx> wrote:

> Hi,
> We were researching Openstack for our private cloud, and want to share
> experience and get tips from community as we go on.
> We have settled on DRBD as shared storage platform for our installation.
> LVM is used over the drbd device to mange logical volumes. OCFS2 file system
> is created on one of volumes, mounted and set up as *image_path* and *
> instance_path* in the *nova.conf*, other space is reserved for storage
> volumes (managed by nova-volume).
> As a result, we have shared storage suitable for features such as live
> migration and snapshots. We also have some level of fault-tolerance, with
> DRBD I/O error handling, which automatically redirects I/O requests to peer
> node over network in case of primary node failure. We created script<https://github.com/Mirantis/openstack-utils/blob/master/recovery_instance_by_id.py>for bootstrapping lost VMs in two crash scenarios:
> * dom0 host restart/domU failure: restore VMs on the same host
> * dom0 host failure: restore VMs on peer node
> We are considering such pair of servers with shared storage as a basic
> block for the cloud structure.
> For whom it may interest, the details of DRBD installation are here<http://mirantis.blogspot.com/2011/05/shared-storage-for-openstack-based-on.html>.
> I'll be glad to answer any questions and highly appreciate feedback on this.
> Oleg S. Gelbukh,
> Mirantis Inc.
> www.mirantis.com
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