[ovirt-users] global vs local maintenance with single host

[Gervais de Montbrun]

Hi Gianluca,

Instead of editing the system's built in systemd configuration, you can do the following...

Create a file called /etc/systemd/system/ovirt-ha-broker.service

# My custom ovirt-ha-broker.service config that ensures NFS starts before ovirt-ha-broker.service
# thanks Gervais for this tip!  :-)

.include /usr/lib/systemd/system/ovirt-ha-broker.service

[Unit]
After=nfs-server.service

Then disable and enable ovirt-ha-broker.service (systemctl disable ovirt-ha-broker.service ; systemctl enable ovirt-ha-broker.service) and you should see that it is using your customized systemd unit definition. You can see that systemd is using your file by running systemctl status ovirt-ha-broker.service. You'll see something like "Loaded: loaded (/etc/systemd/system/ovirt-ha-broker.service;" in the output.

Your file will survive updates and therefore always wait for nfs to start prior to starting. You can do the same for your other customizations.

Cheers,
Gervais



> On Sep 28, 2016, at 1:31 PM, Gianluca Cecchi <gianluca.cecchi at gmail.com> wrote:
> 
> On Sun, Sep 4, 2016 at 10:54 AM, Yedidyah Bar David <didi at redhat.com <mailto:didi at redhat.com>> wrote:
> On Sat, Sep 3, 2016 at 1:18 PM, Gianluca Cecchi
> <gianluca.cecchi at gmail.com <mailto:gianluca.cecchi at gmail.com>> wrote:
> > Hello,
> > how do the two modes apply in case of single host?
> > During an upgrade phase, after having upgraded the self hosted engine and
> > leaving global maintenance and having checked all is ok, what is the correct
> > mode then to put host if I want finally to update it too?
> 
> The docs say to put hosts to maintenance from the engine before upgrading them.
> 
> This is (also) so that VMs on them are migrated away to other hosts.
> 
> With a single host, you have no other hosts to migrate VMs to.
> 
> So you should do something like this:
> 
> 1. Set global maintenance (because you are going to take down the
> engine and its vm)
> 2. Shutdown all other VMs
> 3. Shutdown engine vm from itself
> At this point, you should be able to simply stop HA services. But it
> might be cleaner to first set local maintenance. Not sure but perhaps
> this might be required for vdsm. So:
> 4. Set local maintenance
> 5. Stop HA services. If setting local maintenance didn't work, perhaps
> better stop also vdsm services. This stop should obviously happen
> automatically by yum/rpm, but perhaps better do this manually to see
> that it worked.
> 6. yum (or dnf) update stuff.
> 7. Start HA services
> 8. Check status. I think you'll see that both local and global maint
> are still set.
> 9. Set maintenance to none
> 10. Check status again - I think that after some time HA will decide
> to start engine vm and should succeed.
> 11. Start all other VMs.
> 
> Didn't try this myself.
> 
> Best,
> --
> Didi
> 
> Hello Didi,
> I would like to leverage the update I have to do on 2 small different lab environments to crosscheck the steps suggested.
> They are both single host environments with self hosted engine.
> One is 4.0.2 and the other is 4.0.3. Both on CentoS 7.2
> I plan to migrate to the just released 4.0.4
> 
> One note: in both environments the storage is NFS and is provided by the host itself, so a corner case (for all hosted_storage domain, main data domain and iso storage domain).
> I customized the init scripts, basically for start phase of the server and to keep in count of the NFS service, but probably something has to be done for stop too?
> 
> 1) In /usr/lib/systemd/system/ovirt-ha-broker.service
> 
> added in section [Unit]
> 
> After=nfs-server.service
> 
> The file is overwritten at update so one has to keep in mind this
> 
> 2) also in vdsmd.service changed 
> from:
> After=multipathd.service libvirtd.service iscsid.service rpcbind.service \
>       supervdsmd.service sanlock.service vdsm-network.service
> 
> to:
> After=multipathd.service libvirtd.service iscsid.service rpcbind.service \
>       supervdsmd.service sanlock.service vdsm-network.service \
>       nfs-server.service
> 
> Do you think any order setup I have to put in place related to NFS service and oVirt services stop?
> 
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