Yes, we did exactly the same and do not have practically any problems except some
minor issues with recreatind VMs.
At first, OpenNebula use specified in a template ceph monitors only when creating VM
or migrating it. This template values passed as qemu parameters, when bootstrapping
VM. When VM is running, rbd layer get active monitors from within monmap,
that available for all clients and reflects current configuration of cluster. So we
successfully move all 3 mons from one host group to another with VM running.
The two issue we faced is:
1. When live nigrating VM, OpenNebula use a template to create suspended VM on
target host, and if template contains old monitors, migration fails.
2. Monitor list copied from datastore definition to a template ONLY when you create
template. The template DO NOT REFLECT any further changes, that you do with
your datastore definition when migrationg mointors. So VM restart is not sufficient,
when you change your monitors - you need to recreate a template also.
PS: We use OpenNebula 4.8.
Megov Igor
CIO, Yuterra
Отправлено: 30 сентября 2015 г. 12:20
Кому: ceph-users@xxxxxxxxxxxxxx
Тема: Changing monitors whilst running OpenNebula VMs
Hi,
I have also posted on the OpenNebula community forum (https://forum.opennebula.org/t/changing-ceph-monitors-for-running-vms/1266).
Does anyone have any experience of changing the monitors in their Ceph cluster whilst running OpenNebula VMs?
We have recently bought new hardware to replace our old Ceph monitors, I have replaced two of the three monitors in the Ceph cluster (one at a time, adding one then removing one). I have updated the CEPH_HOST property of our OpenNebula datastore and newly launched VMs pick this up and use the right mons. However VMs instantiated before I made this change are still using the old mons for CEPH_HOST. In practice they are all talking to the one original mon remaining as the others are no longer in the Ceph cluster and are now shutdown. I would very much like to migrate these remaining VMs to using the new mons, as I would like to remove the remaining old one (and it is precarious having them rely on a single host).
George Ryall
Scientific Computing | STFC Rutherford Appleton Laboratory | Harwell Oxford | Didcot | OX11 0QX
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