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Re: OpenStack automate replication


W dniu 02.04.2011 22:44, Jesse Andrews pisze:
What to do when an instance dies is application specific.

Some applications may not care, autoscaling back to the proper size by
themselves.  Other applications may need the resources to be returned in
the most recent state.

Currently openstack requires the user to handle recovery.

Is there any API/modules/scripts for monitoring instances from the OpenStack level? I am indeed looking for the possibility to have the simple HA from the OpenStack level. Suppose, monitor all the instances within single project, and when the instance dies, try automatically running the same instance on different server. The data is now lost, but at least it will serve it's functions (let assume this is a big calculator, that doesn't have to keep any session or user data). When the old instance is available again (maybe the server had some problems with the network) close the new instance down and release resources.

I expect there will be an option to mark a virtual machine as "HA" which
would attempt to relaunch on crashes.  How exactly to implement it will
depend on the cloud requirements. If the instances are backed to a SAN
or distributed filesystem (like ceph) the VM can be relaunched with all
state that has been flushed to disk.  On a cloud with local disk only,
the scheduled snapshotting could allow the vm to a recent state.

nova objectstore doesn't do any data replication? Or it does but only raw system images?

Or HA could mean relaunch the image (ala autoscale)
Does OpenStack itself provide such features or admins of particular VM instances should install and configure HA apps?

What use case are you thinking about?

I assume this is cloude, so when I (let's say I am customer) have my VM with some unix flavour system I don't care whether the server that hosts my VM is down or not. I should be able to connect to the VM that's running in the cloud, not the specific hardware server, am I right?