Open Stack

On 04/14/2014 10:20 AM, Jay Pipes wrote:
> On Mon, 2014-04-14 at 07:45 -0700, Clint Byrum wrote:
>> Excerpts from Russell Bryant's message of 2014-04-14 07:18:49 -0700:
>>> On 04/14/2014 09:45 AM, Jiangying (Jenny) wrote:
>>>> Pacemaker provides the high availability for openstack infrastructure.
>>>>
>>>> We'd like to deliver the vm-level HA to improve the business continuity
>>>> with openstack.
>>>>
>>>> Besides host failure, Our HA mechanism can detect and report host
>>>> isolation, network partition as well as ha agent down.
>>>>
>>>> Ha agent is placed on every node of the system. The master agent is
>>>> elected automatically on system startup and others will be regarded as
>>>> the slave.
>>>>
>>>> For the host states detection, the ha agents communicates through the
>>>> storage subsystem as well as over the management network. Multiple
>>>> communication paths enable better assessment of the health of the host.
>>>> On host failure, the master agent selects the candidate hosts and calls
>>>> the slave ha agents. The slave ha agents talk to the nova compute to
>>>> restart the virtual machine. The master agent reacts to ha agent down by
>>>> reporting to the administrator. During the network partition or host
>>>> isolation event, the HA mechanism will not interrupt the virtual
>>>> machines and just keep them running.
>>>>
>>>> For the virtual machine detection, the ha agents relies on nova compute
>>>> for the information about virtual machines.
>>>>
>>>> Please let me know your comments on this.
>>> In the past we've pushed back on this pretty heavily because it isn't
>>> really relevant for new cloud-style architectures.  The push on this
>>> functionality from a lot of users is pretty insistent so I expect it to
>>> be added at some point in some way, it's just a question of the most
>>> appropriate way.
>>>
>>> What I would like to see is to *not* have this be in Nova.  I'd like to
>>> make sure Nova exposes all necessary information and actions through the
>>> API to make implementing this possible.  However, I think the
>>> functionality generally belongs as something outside of Nova.
>>>
>>> If it's something that lives outside of Nova, then we should discuss it
>>> in terms of public APIs (whether that's Nova's API, or a combination of
>>> Nova and Ceilometer, perhaps).
>>>
>> For the most part we've been trying to encourage projects that want to
>> control VMs to add such functionality to the Orchestration program, aka
>> "Heat".
> Yes, exactly.
>
> -jay
>
Hey folks,

Just as a note for HA for VMs, our current heat-core thinking is our 
HARestarter resource functionality is a workflow (Restarter is a verb, 
rather then a Noun - Heat orchestrates Nouns) and would be better suited 
to a workflow service like Mistral.  Clearly we don't know how to get 
from where we are today to the proper separation of concerns as pointed 
out by Zane Bitter in recent threads on the ml but just throwing this 
out there so folks are aware.

Regards
-steve

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