[openstack-dev] deliver the vm-level HA to improve the business continuity with openstack

Russell Bryant rbryant at redhat.com
Mon Apr 14 14:18:49 UTC 2014


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).

-- 
Russell Bryant



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