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

[Gianluca Cecchi]

On Sun, Sep 4, 2016 at 10:54 AM, Yedidyah Bar David <didi at redhat.com> wrote:

> On Sat, Sep 3, 2016 at 1:18 PM, Gianluca Cecchi
> <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
>

I tested on one of the 2 environments.
It seems it worked.
But I update the kernel on host without restarting it. I would try that
with the other one.
Some notes:

8. Check status. I think you'll see that both local and global maint
are still set.

Actually even if I'm on global maintenance and then I set local
maintenance, it seems I "loose" the global maintenance state...

I see this output, without the line with Global Maintenance and exclamation
marks....:

[root at ractor ~]# hosted-engine --vm-status
/usr/lib/python2.7/site-packages/ovirt_hosted_engine_ha/lib/storage_backends.py:15:
DeprecationWarning: vdscli uses xmlrpc. since ovirt 3.6 xmlrpc is
deprecated, please use vdsm.jsonrpcvdscli
  import vdsm.vdscli


--== Host 1 status ==--

Status up-to-date                  : False
Hostname                           : ractor.mydomain
Host ID                            : 1
Engine status                      : unknown stale-data
Score                              : 0
stopped                            : False
Local maintenance                  : True
crc32                              : d616dde1
Host timestamp                     : 3304360
Extra metadata (valid at timestamp):
    metadata_parse_version=1
    metadata_feature_version=1
    timestamp=3304360 (Mon Oct  3 22:27:07 2016)
    host-id=1
    score=0
    maintenance=True
    state=LocalMaintenance
    stopped=False
[root at ractor ~]#


I'm able to exit maintenance, connect to engine and start the other VMs.
Now I have to try considering also the restart of the hypervisor host, due
to new kernel package install.

Gianluca
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