On 2011-07-11 15:14, Ulrich Windl wrote:
>>>> Florian Haas <[email protected]> schrieb am 11.07.2011 um 14:12 in
> Nachricht <[email protected]>:
>> On 2011-07-11 13:40, Ulrich Windl wrote:
>>> Hi!
>>>
>>> I think I misunderstood "colocation": I thought a colocation means if two 
>> resources are running, the should be (or not) on the same node.
>>> In practive however, there seems to be more:
>>> I have two resources, say A and B. A has highter priority than B, and an 
>> ordering that B should be started after A. As B depends on resources 
>> provided 
>> by A, I also added a infnity colocation for A and B.
>>> Now I'm surprised that when I tell CRM to stop B, B is stopped, but A also.
>>
>> It would be helpful if you shared your configuration, rather than
>> paraphrased it. That way we could have figured out if your configuration
>> actually matches the blurb you posted.
> 
> OK:
> primitive prm_rksapr00_ping ocf:pacemaker:ping \
>         params ... \

Any specific reason why you're cutting configuration parameters out?

>         op monitor interval="300s" timeout="60" \
>         op start interval="0" timeout="60" \
>         utilization utl_cpu="1" utl_ram="1" \
>         meta priority="2050" target-role="Started"
> group grp_rksapr00 prm_rksapr00_ip_1 ... \

Here too?

>         meta priority="2000" resource-stickiness="100000" 
> target-role="Started"
> order ord_rksapr00_ping_after_saprouter inf: grp_rksapr00 prm_rksapr00_ping
> colocation col_rksapr00_saprouter_ping inf: grp_rksapr00 prm_rksapr00_ping

Why is the ping resource not cloned, and what is this colocation
supposed to achieve?

>> It is non-obvious, from your description, how you set a "higher
>> priority" for one resource over another, whether your order constraint
>> is advisory or mandatory, how you placed your colocation constraint, etc.
>>
>>> I wanted B to be more independent of A compared to putting A and B into one 
>> group.
>>>
>>> What did I misunderstand?
>>
>> You probably (I'm guessing) missed the fact that colocation constraints
>> are directional. They are not reversible at will.
>>
>> If you have a colocation constraint like
>>
>> inf: foo bar
>>
>> ... then verbalize this as "foo on bar". foo must always run "on bar",
>> that is to say, on whichever node is currently managing bar. What this
>> implies is that if bar isn't running anywhere, foo can't run, either. By
>> contrast if foo can't run anywhere, then bar is unaffected.
> 
> OK, so it seems you implemented a strange kind of c "colocation" that is part 
> of co-location, and part of "depends_on". I'd like to have clean and separate 
> implementations:

Excellent. Send a patch!

> For co-location: If "A is near B", obviously "B is near A", so co-location is 
> symmetric by nature.
> 
> For "depends_on": if "A depends_on B" it makes not much sense if "B 
> depends_on A" (is this antisymmetric?)
> 
> Your implementation mixed both, a symmetric and a non-symmetric relation. 
> Naturally this causes problems.

Out of curiosity, to whom does the possessive pronoun apply?

> Well actually I feel you just don't like any opinion others than your own.

Says exactly who, about whom?

Anyhow, naturally you are entitled to feeling whatever you like.

> It's not that I want to be right; it's just that I feel I'm right.

Oh! Well then of course I'll rest my case.

Florian



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