[DRBD-user] DRBD demote/promote not called - Why? How to fix?

CART Andreas andreas.cart at sonorys.at
Fri Nov 25 18:58:39 CET 2016

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


To: drbd-user at lists.linbit.com Lars Ellenberg wrote:
On Mon, Nov 14,2016 at 10:12
>On Sat, Nov 12, 2016 at 09:45:39AM +0000, CART Andreas wrote:
>> On Thu, Nov 10,2016 at 13:21
>> To: drbd-user at lists.linbit.com Lars Ellenberg wrote:
>> > On Thu, Nov 10, 2016 at 12:05:09PM +0000, CART Andreas wrote:
>> >> I again started with all resources located at ventsi-clst1 and 
>> >> issued a 'pcs resource move DRBD_global_clst' (the resource next 
>> >> collocated next to the DRBDClone).
>> >> 
>> >> With that I end up with all primitive resources stopped and the 
>> >> DRBDClone resource still being master at ventsi-clst1.
>> >
>> > I don't think that has anything to do with DRBD, (you'll see that 
>> > when you try with some dummy resources instead).
>> >
>> > Just moving something "top of the dependency chain" won't move the 
>> > bottom of the dependency chain, especially not a Master role.
>> > This is a Pacemaker shortcoming.
>> 
>> I am pretty sure that's not generally true (although I'm new to DRBD 
>> and pacemaker and always willing to learn).
>
> Prepare a cib with dummy resources (ocf:pacemaker:Dummy,
> ocf:pacemaker:Stateful), and add similar constraints, then start experimenting.
>
> If you find suboptimal behaviour, you have a nice little example you can
> show upstream when filing bug fix or enhancement requests for how
> pacemaker "should" deal with certain situations.
>
> If with dummy resources you find behaviour to significantly differ from
> what you get with "real" resources, and the dummy setup behaves "better"
> for your definition of better, you still have a nice
> example to show how you "want" things to behave, and we can more easily
> look into why things don't behave that way with "real" resources.

I did not expect it to be a DRDB-bug but rather a configuration problem
for a very common setup of a clustered NFS server on top of DRBD as it is
documented in numerous writings.
Hopefully someone familiar with this sort of setup would easily point out
the obvious misconfiguration I did not see.

Unfortunately no one here chimed in ... so I had to do it the hard way
... and can now conclude that it's no pacemaker bug or shortcoming  either.

It was simply a configuration problem (as expected).
Anyone interested in the details might have a look at
http://clusterlabs.org/pipermail/users/2016-November/004598.html

Kind regards
Andi



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