[ClusterLabs] Antw: Re: Antw: Re: pacemaker resources under systemd

[Andrei Borzenkov]

On Thu, Sep 12, 2019 at 3:45 PM Ulrich Windl
<Ulrich.Windl at rz.uni-regensburg.de> wrote:
>
> >>> Andrei Borzenkov <arvidjaar at gmail.com> schrieb am 12.09.2019 um 14:21 in
> Nachricht
> <CAA91j0UnCSS08ZKyjYn26eysVKwVVuh4hryF98HN5jK7SEU2UQ at mail.gmail.com>:
> > On Thu, Sep 12, 2019 at 12:40 PM Ulrich Windl
> > <Ulrich.Windl at rz.uni-regensburg.de> wrote:
> >>
> >> Hi!
> >>
> >> I just discovered an unpleasant side-effect of this:
> >> SLES has "zypper ps" to show processes that use obsoleted binaries. Now if
>
> > any
> >> resource binary was replaced, zypper suggests to restart pacemaker (which
> is
> >> nonsense, of course).
> >>
> >> Example:
> >> # zypper ps
> >> The following running processes use deleted files:
> >>
> >> PID    | PPID  | UID | User  | Command           | Service   | Files
> >>
> >
> -------+-------+-----+-------+-------------------+-----------+---------------
> > --------------
> >> 2558   | 92480 | 0   | root  | isredir (deleted) | pacemaker |
> >> /usr/bin/isredir (deleted)
> >>
> >> The file definitely is not a part of pacemaker!
> >>
> >
> > Neither zypper tells you that it is. All that zypper tells you is that
> > binary of some process that was started as part of pacemaker *SERVICE*
> > was deleted and that if you want to refresh it and ensure that process
> > is using updated binary you need to restart *SERVICE* pacemaker. Which
>
> That is exactly the point: You DO NOT need to restart pacemaker; it is
> sufficient to restart the corresponding resource.
>
> > is absolutely correct. Restarting pacemaker service makes sure
> > everything used by pacemaker is up to date. That pacemaker is capable
> > of restarting only some processes is not known to zypper. While it
> > sure is possible to extend zypper to recognize pacemaker, parse
> > current configuration and suggest to restart specific resource, this
> > time is probably better spent somewhere else.
>
> You absolutely miss the point:

I do not.

> In a 24x7 environment (a classic  cluster
> application) restarting pacemaker means that every resource is stopped and
> restarted. If you do it in maintenance mode, the resources will not be
> restarted, but also the problem will not go away. Not restarting pacemaker is
> worth the time!
>

This is common misconception. Your 24x7 environment must have planned
maintenance windows exactly so you can do maintenance that requires
stopping and starting process/services/systems. And in such critical
environments updates are not installed at arbitrary times, but during
these maintenance windows.

But sure, if zypper can do better, that's fine. I am just not sure
whether zypper developers can be reached on this forum ...