[Pacemaker] placement-strategy=minimal - placing and logging

[Lars Marowsky-Bree]

On 2013-03-08T17:43:54, Vladimir <ml at foomx.de> wrote:

> I already had to work around utilization by defining utilization for
> the first resource in the Resource Group. Defining utilization for
> Resource Groups didn't work for me. Furthermore I can remember that
> there were also problems by colocating Resource Groups. I would like to
> stay by the given resource layout.

Allocation of resource groups with utilization has been improved in
1.1.9. (i.e., it now sums up the resources properly and allocates the
group as a whole; even though it internally works just as you describe
by transferring the whole load to the first resource.)

> What are your experience? Is it possible to combine Resource Groups and
> colocations? Or do I have to give up Resource Groups when using
> colocations? If so I maybe have to restructure my resource setup to
> colocations only.

You can combine them fine.

> That could be an approach. Sorry if a beginner question but I know
> policy engine only in form of ptest command. Did you think to parse
> the output of ptest and crm_mon?

Yes.

> Or do you see a more straight forward way to monitor the cluster
> state?

It depends on what you want to do. You can add a log message to pengine
source code to indicate when a resource wasn't placed based on
utilization; or similarly, indicate the reason why a resource is "not
running" (as far as the PE can tell) in crm_mon (and then possibly
hawk). That makes perfect sense, but none of the tools do that today.

So it's either modifying the code or writing some code that deduces it
from ptest output.


Regards,
    Lars

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