openstack team mailing list archive

[Nelson Nahum <nelson@xxxxxxxxxxxxxxxxx>]

At Zadara Storage, we are working on a block storage system for the cloud.
We didn't published much info yet but if somebody is interested I will be
happy to be in a call and explain what we are doing.

Nelson Nahum
CTO
nelson@xxxxxxxxxxxxxxxxx


2011/5/27 Oleg Gelbukh <ogelbukh@xxxxxxxxxxxx>

> Hi
> Our approach was defined by need to combine storage and compute on the same
> hosts.
> Our configuration is dual-primary, so we can run nova-compute and virtual
> servers on both nodes and have them with write access to volumes. DRBD
> allows this mode out-of-box now, but it requires clustered file system or
> great caution when runnning LVM on it.
> But nova-volume must run on one node of drbd-connected pair, while the
> second gets copy of lvm data via drbd. The tricky part is that it seems we
> must activate volumes and volume groups on the peer node, but automation of
> this is relatively easy.
> For now, we are not going to share volumes outside of drbd-peers pair for
> live migration or as attachable volumes, except some special cases like
> migrating VMs between drbd pairs.
> Looking forward to read couple of words on your approach.
>
> 2011/5/26 Diego Parrilla Santamaría <diego.parrilla.santamaria@xxxxxxxxx>
>
>> 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.
>>
>> Regards
>> Diego
>>
>> --
>> Diego Parrilla
>> <http://www.stackops.com>*CEO*
>> *www.stackops.com | * diego.parrilla@xxxxxxxxxxxx** | +34 649 94 43 29 |
>> skype:diegoparrilla*
>> * <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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>>>
>>
>
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