[Linux-cluster] Monitoring services/customize failure criteria

[Jeff Stoner]

> -----Original Message-----
> It is also the detail of status/monitor which implementers get most
> frequently wrong. "But it's either running or not!" ... Which 
> is clearly
> not true, or at least such a case couldn't protect against certain
> failure modes. (Such as multiple-active on several nodes, which is
> likely to be _also_ failed.)

Ok. I think I understand where the confusion lies.

LSB is strictly for init scripts.
OCF is strictly for a cluster-managed resource.

They are similar but have significant differences. For example, LSB
scripts are required to implement a 'status' action while OCF scripts
are required to implement a 'monitor' action. This difference alone
means, technically, you can't interchange LSB and OCF scripts unless
they implement both (in some fashion.)

I think this is the missing link in our conversation: the script
resource type in Cluster Services is an attempt to make a LSB-compliant
script into a OCF-compliant script. So, the /usr/share/cluster/script.sh
expects the script you specify to behave like an LSB script, not an OCF
script. As such, the script resource type falls back to LSB conventions
and uses a binary approach to a resource's start/stop/status actions:
zero for success and non-zero for any failure. Other resource types
(file system, nfs, ip, mysql, samba, etc.) may implement full OCF RA API
exit codes.

Does this help?

--Jeff
Performance Engineer

OpSource, Inc.
http://www.opsource.net
"Your Success is Our Success"