[ClusterLabs] Q: ordering for a monitoring op only?

Ryan Thomas developmentrjt at gmail.com
Tue Aug 21 11:38:33 EDT 2018

You could accomplish this be creating a custom RA which normally acts as a
pass-through and calls the "real" RA.  However, it intercepts "monitor"
actions, checks nfs, and if nfs is down it returns success, otherwise it
passes though the monitor action to the real RA.  If nfs fails the monitor
action is in-flight, the customer RA can intercept the failure, check if
nfs is down, and if so change the failure to a success.

On Mon, Aug 20, 2018 at 3:51 AM Ulrich Windl <
Ulrich.Windl at rz.uni-regensburg.de> wrote:

> Hi!
> I wonder whether it's possible to run a monitoring op only if some
> specific resource is up.
> Background: We have some resource that runs fine without NFS, but the
> start, stop and monitor operations will just hang if NFS is down. In effect
> the monitor operation will time out, the cluster will try to recover,
> calling the stop operation, which in turn will time out, making things
> worse (i.e.: causing a node fence).
> So my idea was to pause the monitoing operation while NFS is down (NFS
> itself is controlled by the cluster and should recover "rather soon" TM).
> Is that possible?
> And before you ask: No, I have not written that RA that has the problem; a
> multi-million-dollar company wrote it (Years before I had written a monitor
> for HP-UX' cluster that did not have this problem, even though the
> configuration files were read from NFS (It's not magic: Just periodically
> copy them to shared memory, and read the config from shared memory).
> Regards,
> Ulrich
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