On Wed, Mar 27, 2013 at 2:38 AM, Robinson, Eric <[email protected]> wrote:
>> > In the simplest terms, we currently have resources:
>> >
>> > A = drbd
>> > B = filesystem
>> > C = cluster IP
>> > D thru J = mysql instances.
>> >
>> > Resource group G1 consists of resources B through J, in
>> that order, and is dependent on resource A.
>> >
>> > This fails over fine, but it has the serious disadvantage
>> that if you stop or remove a mysql resource in the middle of
>> the list, all of the ones after it stop too. For example, if
>> you stop G, then H thru J stop as well.
>> >
>> > We want to change it so that the resource group G1 consists
>> only of resources B & C. All of the mysql instances (D thru
>> J) are individually dependent on group G1, but not dependent
>> on each other. That way you can stop or remove a mysql
>> resource without affecting the others.
>> >
>> > I saw this scenario described in the Pacemaker docs, but I
>> cannot find an example of the syntax.
>>
>> You can use two resource-sets and go without groups, with
>> that crm shell
>> syntax:
>>
>> order o_drbd-filesystem-ip-dbs inf: A:promote B C (D E F G H
>> I J) colocate co_all-follow-drbd inf: (D E F G H I J) B C A:Master
>>
>> Regards,
>> Andreas
>>
>
> Oh my gosh, that's what I have been trying to figure out for a year or more. 
> I am very excited to try this. Note that I actually have more like 50 mysql 
> resources, not just 7 like in the example. Will that be a problem?

No.

Did you also consider:

G1 = A, B, C

colocate D with G1
order D after G1

colocate E with G1
order E after G1

...

The set syntax cuts down on the duplication, but the above will also work.

> I read somewhere that there is a limit on the number of resources that can 
> start in parallel. By default it is 4. That's fine as long as they all 
> eventually start.
>
> --Eric
>
>
>
>
>
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