[DRBD-user] Can't Get DRBD Master/Slave out of secondary/secondary using pacemaker

Arnold Krille arnold at arnoldarts.de
Fri Oct 7 21:26:49 CEST 2011

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

On Friday 07 October 2011 13:26:19 Florian Haas wrote:
> On 2011-10-07 10:00, Arnold Krille wrote:
> > On Friday 07 October 2011 09:50:47 Felix Frank wrote:
> >> On 10/07/2011 09:41 AM, Arnold Krille wrote:
> >>> The order on a colocation doesn't matter.
> >> 
> >> funny you should mention "order" in this context. You do in fact want to
> >> add an order constraint for these resources.
> > 
> > I know, but some people didn't want to believe me and said that the order
> > of elements inside the colocation was of any importance.
> I'll make one more attempt at explaining. If your opinion is set and you
> prefer not to be confused with facts, don't read on.
> colocation foo_on_bar inf: foo bar
> means that
> 1. foo is to run wherever bar runs;
> 2. if bar is not started, then foo won't run at all;
> 3. if bar fails and cannot recover, then foo will shut down;
> 4. if foo is not started, bar will of course run;
> 5. if foo fails and cannot recover, bar will continue to run.
> To make the point again with a sledge hammer, of the five (5) aspects
> with which a colocation affects resource management, one (1) is
> identical irrespective of the order in which the resources are listed in
> the colocation definition. The other four (4) are not.

I think I am beginning to understand what you mean. Altough I didn't come to 
this understanding from the docs I read so far.
I will test this in the next days.

Some questions:
 - If the rule is not inf: but something like 100:, what happens when (in your 
first example that I quoted above) bar fails and can not recover? A colocation-
binding with a score of less then inf would leave a chance for foo to run 
without bar or (if other scores are right) to run on a different node than bar, 
 - Your (2) would mean that foo is actually started after bar finished 
starting? Otherwise foo wouldn't know if bar didn't start.

Have a nice weekend,

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