[Pacemaker] Monitor a resource without the cluster reacting to the result...

[Joe Bill]

--- On Thu, 3/26/09, Andrew Beekhof <beekhof at gmail.com> wrote:

>> .... what command should I type to cause the cluster
>> to perform a "monitor" operation at a specific check
>> level on that resource, and return the appropriate
>> OCF status of the operation, *without* the cluster
>> reacting like triggering a failover ? 
>
> Basically this is a bad idea.

:-) 

Sorry Andrew, I'm afraid I'm going to ask you to follow this up with some explanation and arguements.

>
> If you don't want the cluster to react to an event, don't
> have it perform one.
>
Andrew, like any ***serious*** system control software I've seen, the cluster should have switches for testing components ON-LINE.

You don't expect engineers to bring down a nuke plant to test it's components and emergency procedures, do you ?

> I saw later that you want to prevent the cluster
> from doing anything for the resource, simply set
> is-managed=false for the resource in question.

This is incorrect. I want the cluster to react to everything BUT to this specific invocation of MONITOR.

> Then, when you're done with your maintenance, set it back
> to true.

This is like turning off all the nuke plant's alarms while the maintenance teams are cleaning up the keyboards in the control room.

I'm sure we can do better than that.

> 
> There may be a valid need for this one day, but blocking
> other actions for the resource is definitely not it.
>
Blocking but at most to an extent, no ?

Won't the cluster NEVER interrupt an ongoing MONITOR operation beyond a certain amount of time ?

Also what happens if, while a MONITOR operation is going on, I issue a:
"crm_resource -M" on the same resource to migrate it ?

Will the cluster wait until the monitor operation is finished ?