[ClusterLabs] big trouble with a DRBD resource

Lentes, Bernd bernd.lentes at helmholtz-muenchen.de
Wed Aug 9 12:48:01 EDT 2017

----- Am 8. Aug 2017 um 15:36 schrieb Lars Ellenberg lars.ellenberg at linbit.com:
> crm shell in "auto-commit"?
> never seen that.

i googled for "crmsh autocommit pacemaker" and found that: https://github.com/ClusterLabs/crmsh/blob/master/ChangeLog
See line 650. Don't know what that means.
> You are sure you did not forget this necessary piece?
> ms WebDataClone WebData \
>    meta master-max="1" master-node-max="1" clone-max="2"
>    clone-node-max="1" notify="true"

I didn't come so far. I followed that guide (http://clusterlabs.org/doc/en-US/Pacemaker/1.1-plugin/html-single/Clusters_from_Scratch/index.html#_configure_the_cluster_for_drbd),
but didn't use the shadow cib. The cluster is in testing, not in production, so i thought "nothing severe can happen". Misjudged. My error.
After configuring the primitive without the ms clone my resource ClusterMon reacted promptly and sent 20000 snmp traps to my management station in 193 seconds, which triggered 20000 e-Mails ...

I understand now that the cluster missed the ms clone configuration.
But so much traps in such a short period. Is that intended ? Or a bug ?
> If you ever are stuck in a situation like that,
> I suggest you put your cluster in "maintenance mode",
> then fix up your configuration
> (remove the primitive, or add the ms definition),
> do cleanups for "everything",
> simulate the "maintenance mode off",
> and if that looks plausible, commit the maintenance mode off.
> Also, even though that has nothing to do with your issue there:
> just because you *can* do dual-primary DRBD + GFS2 does not mean that it
> is a good idea. That "Cluster from scratch" is a prove of concept,
> NOT a "best practices how to set up a web server on pacemaker and DRBD"
> If you don't have a *very* good reason to use a cluster file
> system, for things like web servers, mail servers, file servers,
> ...  most services actually, a "classic" file system as xfs or
> ext4 in failover configuration will usually easily outperform a
> two-node GFS2 setup, while being less complex at the same time.

I will not use a cluster FS. DRBD is intended as a backing device for a VirtualDomain which resides in a plain volume, without a fs.


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