Re: [ovirt-users] Engine migration and host import

On 20/09/17 15:41, Simone Tiraboschi wrote: > > On Wed, Sep 20, 2017 at 12:30 AM, Ben Bradley <listsbb(a)virtx.net > <mailto:listsbb@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-en... > > > <https://www.ovirt.org/develop/developer-guide/engine/migrate-to-hosted-en... > > and > > https://www.ovirt.org/documentation/self-hosted/chap-Migrating_from_Bare_... > > > <https://www.ovirt.org/documentation/self-hosted/chap-Migrating_from_Bare_... > > > 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. Thank you for the reply. I tried this again this evening - again it failed. The host is present within the new engine but I am unable to manage it. Host is marked as down but Activate is greyed out. I can get get into the "Edit" screen for the host and on right-click I get the following options: - Maintenance - Confirm Host has been Rebooted - SSH Management: Restart and Stop both available The VMs are still running and accessible but are not listed as running under the web interface. This time however I did lose access to the ovirtmgmt bridge and the web interface, running VMs and host SSH session were unavailable until I rebooted. Luckily I left ovirt-engine service enabled to restart on boot so everything came back up. The engine URL is a CNAME so I just re-pointed to the hostname of the VM just before running engine-setup after the restore. This time though I have kept the new engine VM so I can power it up again and try and debug. I am going to try a few times over the weekend and I have setup serial console access so I can do a bit more debugging. What ovirt logs could I check on the host to see if the new engine VM is able to connect and sync to the host properly? Thanks, Ben

> 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 > _______________________________________________ > Users mailing list > Users(a)ovirt.org <mailto:Users@ovirt.org> > http://lists.ovirt.org/mailman/listinfo/users > <http://lists.ovirt.org/mailman/listinfo/users> > > _______________________________________________ Users mailing list Users(a)ovirt.org http://lists.ovirt.org/mailman/listinfo/users