[Pacemaker] asymmetric clusters, remote nodes, and monitor operations

[Andrew Beekhof]

On 04/09/2013, at 6:18 AM, Lindsay Todd <rltodd.ml1 at gmail.com> wrote:

> We've been attempting to set up an asymmetric pacemaker cluster using remote cluster nodes, with pacemaker 1.1.10 (actually, building from git lately, currently at a4eb44f).  We use location constraints to enable resources to start on nodes they should start on, and rely on asymmetry to otherwise keep resources from starting.

You set symmetric-cluster=false or assumed that was the default

> 
> But we get many monitor operation failures.
> 
> Resource monitor operations run on the physical real hosts, and frequently fail because not all the components are present on those hosts.  For instance, the mysql resource agent's monitor operation fails as "not installed", since, well, mysql isn't installed on those systems, so the validate operation, which most or every path through that agent runs, always fails.  I don't see failures on the remote nodes, even ones without mysql installed.
> 
> Previously I'd noticed LSB resources had failed monitor operations on systems that didn't have the LSB init script installed.
> 
> Presumably these monitor operations are happening to ensure the resource is NOT running where it should not be???

Correct. Although with symmetric-cluster=false it shouldn't show up as an error.
Logs? crm_mon output? 

>  There doesn't seem to be a way to set up location constraints to prevent this from happening, at least that I've found.  I wrote an OCF wrapper RA to help me with LSB init scripts, but not sure what to do about other RA's like mysql short of maintaining my own version, unless there is a way to tune where "monitor" runs.  Or more likely I'm missing something ...
> 
> It would seem to me that a "not installed" failure, OCF_ERR_INSTALLED, would not really be an error on a node that shouldn't be running that resource agent anyway, and is probably a pretty good indication that it isn't running.
> 
> /Lindsay
> 
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