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

CART Andreas andreas.cart at sonorys.at
Sat Nov 12 10:45:39 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:
Subject: Re: [DRBD-user] DRBD demote/promote not called - Why? How to fix?
On Thu, Nov 10,2016 at 13:21, 
> 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).

> You can have depending resources follow a Master role,
> but Pacemaker is not "smart enough" to recognize moving the Master role
> would help with starting the resources you moved to some other node.

In general pacemaker seems to consider the complete dependency chain including resource promotion - at  least that's what some tests showed.

> Workaround:
> move the master role, or something the master role depends on.

I can confirm that resource movement is working if I move the DRBD clone resource, but that's only a possible workaround in case of manual movement.
In case of a resource failure detection the cluster has to move the complete resource chain in any case - even in case another resource than the DRBD clone resource fails.

Kind regards
Andi



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