[ClusterLabs] Antw: Re: Antw: [EXT] Re: Order set troubles

[Andrei Borzenkov]

On Fri, Mar 26, 2021 at 10:17 AM Ulrich Windl
<Ulrich.Windl at rz.uni-regensburg.de> wrote:
>
> >>> Andrei Borzenkov <arvidjaar at gmail.com> schrieb am 26.03.2021 um 06:19 in
> Nachricht <534274b3-a6de-5fac-0ae4-d02c305f1a3f at gmail.com>:
> > On 25.03.2021 21:45, Reid Wahl wrote:
> >> FWIW we have this KB article (I seem to remember Strahil is a Red Hat
> >> customer):
> >>   - How do I configure SAP HANA Scale-Up System Replication in a Pacemaker
> >> cluster when the HANA filesystems are on NFS shares?(
> >> https://access.redhat.com/solutions/5156571)
> >>
> >
> > "How do I make the cluster resources recover when one node loses access
> > to the NFS server?"
> >
> > If node loses access to NFS server then monitor operations for resources
> > that depend on NFS availability will fail or timeout and pacemaker will
> > recover (likely by rebooting this node). That's how similar
> > configurations have been handled for the past 20 years in other HA
> > managers. I am genuinely interested, have you encountered the case where
> > it was not enough?
>
> That's a big problem with the SAP design (basically it's just too complex).
> In the past I had written a kind of resource agent that worked without that
> overly complex overhead, but since those days SAP has added much more
> complexity.
> If the NFS server is external, pacemaker could fence your nodes when the NFS
> server is down as first the monitor operation will fail (hanging on NFS), the
> the recover (stop/start) will fail (also hanging on NFS).

And how exactly placing NFS resource under pacemaker control is going
to change it?

> Even when fencing the
> node it would not help (resources cannot start) if the NFS server is still
> down.

And how exactly placing NFS resource under pacemaker control is going
to change it?

> So you may end up with all your nodes being fenced and the fail counts
> disabling any automatic resource restart.
>

And how exactly placing NFS resource under pacemaker control is going
to change it?