On Wed, Sep 20, 2017 at 12:30 AM, Ben Bradley <listsbb(a)virtx.net> wrote:
Hi All
I've been running a single-host ovirt setup for several months, having
previously used a basic QEMU/KVM for a few years in lab environments.
I currently have the ovirt engine running at the bare-metal level, with
the box also acting as the single host. I am also running this with local
storage.
I now have an extra host I can use and would like to migrate to a hosted
engine. The following documentation appears to be perfect and pretty clear
about the steps involved:
https://www.ovirt.org/develop/
developer-guide/engine/migrate-to-hosted-engine/ and
https://www.ovirt.org/documentation/self-hosted/chap-Migrati
ng_from_Bare_Metal_to_an_EL-Based_Self-Hosted_Environment
However I'd like to try and get a bit more of an understanding of the
process that happens behind the scenes during the cut-over from one engine
to a new/hosted engine.
As an experiment I attempted the following:
- created a new VM within my current environment (bare-metal engine)
- creating an engine-backup
- stopped the bare-metal engine
- restored the backup into the new VM
- ran engine-setup within the new VM
The new engine started up ok and I was able to connect and login to the
web UI. However my host was "unresponsive" and I was unable to manage it in
any way from the VM. I shut the VM down and started the bare-metal
ovirt-engine again on the host and everything worked as before. I didn't
try very hard to make it work however.
The magic missing from the basic process I tried is the synchronising and
importing of the existing host, which is what the hosted-engine utility
does.
No magic up to now: the host are simply in the DB you restored.
If the VM has network connectivity and the same host-name of the old
machine you shouldn't see any issue.
If you changed the host-name moving to the VM, you should simply run
engine-rename after the restore.
The only detail is that hosted-engine-setup will try to add the host where
you are running it to the engine and so you have to manually remove it just
after the restore in order to avoid a failure there.
Can anyone describe that process in a bit more detail?
Is it possible to perform any part of that process manually?
I'm planning to expand my lab and dev environments so for me it's
important to discover the following...
- That I'm able to reverse the process back to bare-metal engine if I ever
need/want to
- That I can setup a new VM or host with nothing more than an
engine-backup but still be able to regain control of exiting hosts and VMs
within the cluster
My main concern after my basic attempt at a "restore/migration" above is
that I might not be able to re-import/sync an existing host after I have
restored engine from a backup.
I have been able to export VMs to storage, remove them from ovirt,
re-install engine and restore, then import VMs from the export domain. That
all worked fine. But it involved shutting down all VMs and removing their
definitions from the environment.
Are there any pre-requisites to being able to re-import an existing
running host (and VMs), such as placing ALL hosts into maintenance mode and
shutting down any VMs first?
Any insight into host recovery/import/sync processes and steps will be
greatly appreciated.
Best regards
Ben
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