[Pacemaker] crm_simulate a resource failure
Cal Heldenbrand
cal at fbsdata.com
Wed Oct 24 14:37:27 UTC 2012
Thanks Andrew! My first few attempts at playing around with the failure
states are working as expected.
A few follow-ups below:
--op-fail isn't the command you want though.
> From the man page:
>
> -i, --op-inject=value
> $rsc_$task_$interval@$node=$rc - Inject the specified
> task before running the simulation
>
> -F, --op-fail=value
> $rsc_$task_$interval@$node=$rc - Fail the specified task
> while running the simulation
>
> Note the difference between the two descriptions: before vs. while.
> --op-inject is the one you want. It is mostly useful for pretending a
> recurring monitor failed and seeing what the cluster would do about
> it.
>
> --op-fail on the other hand, is used for pretending that part of the
> recovery process failed.
>
Your follow up description here is great, and makes more sense. I was
reading "Fail the specified task" as literally, "here's my task, fail it
and show me the results" I'd suggest to add a little paragraph in the man
page to elaborate these points too. Also, can you tell me what all of the
return codes are? Do I have to use integers, or do strings like "error"
work?
While we're on the subject of documentation / usability, I would also
suggest to split out these two features into more parameters. (What would
happen if I named my resource with an underscore?) Maybe something like:
--op-pre-resource=[primitive name]
--op-pre-task=[monitor|start|stop]
--op-pre-interval=[integer]
--op-pre-node=[hostname]
--op-pre-rc=[error|timeout|other stuff]
Then have similar --op-post-* parameters. Or whatever verbs make the most
sense in the spirit of Pacemaker vocabulary. (pre/post, before/after,
inject/fail, input/output, etc) And, examples are always awesome in man
pages too.
Of course, this is all great future version stuff, but that doesn't help
all of the RedHat 6 people that will be using pacemaker 1.1 packages for
the next ~10 years until RedHat 7 comes out. So I suppose documenting the
old code in the online docs is a Good Thing. :-)
Thanks again!
--Cal
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