[ClusterLabs] What am I Doing Wrong with Constraints?

[Ken Gaillot]

On Mon, 2018-08-06 at 17:02 +0000, Eric Robinson wrote:
> I don't understand why a problem with a resource causes other
> resources above it in the dependency stack (or on the same level with
> it) to fail over.
> 
> My dependency stack is:
> 
> drbd -> filesystem -> floating_ip -> Azure virtual IP
> 			|
> 			-> MySQL_instance_1
> 			-> MySQL_instance_2
> 
> Note that the MySQL instances are dependent on the floating IP, but
> not on each other. However, if one of the MySQL instances has a
> problem that causes it to go into a FAIL status, the whole cluster
> fails over. Or if the Azure virtual IP resource has a problem and I
> need to run a cleanup, the whole cluster fails over. 

That shouldn't happen, and there's nothing wrong with your
configuration as posted here. (The configuration here shows only one
mysql instance, but I assume the second would be configured the same
when present.)

You'll need to look at the logs (ideally the pacemaker detail log, but
syslog is ok) from both nodes around the time of the failure to
investigate further.

> 
> Here's what my resources look like...
> 
> [root at 001db01b mysql]# pcs status
> Cluster name: 001db01ab
> Stack: corosync
> Current DC: 001db01b (version 1.1.18-11.el7_5.3-2b07d5c5a9) -
> partition with quorum
> Last updated: Mon Aug  6 12:52:44 2018
> Last change: Mon Aug  6 12:18:38 2018 by root via cibadmin on
> 001db01a
> 
> 2 nodes configured
> 11 resources configured
> 
> Online: [ 001db01a 001db01b ]
> 
> Full list of resources:
> 
>  p_vip_clust01  (ocf::heartbeat:IPaddr2):       Started 001db01b
>  p_azip_clust01 (ocf::heartbeat:AZaddr2):       Started 001db01b
>  Master/Slave Set: ms_drbd0 [p_drbd0]
>      Masters: [ 001db01b ]
>      Slaves: [ 001db01a ]
>  Master/Slave Set: ms_drbd1 [p_drbd1]
>      Masters: [ 001db01a ]
>      Slaves: [ 001db01b ]
>  p_fs_clust01   (ocf::heartbeat:Filesystem):    Started 001db01b
>  p_fs_clust02   (ocf::heartbeat:Filesystem):    Started 001db01a
>  p_vip_clust02  (ocf::heartbeat:IPaddr2):       Started 001db01a
>  p_azip_clust02 (ocf::heartbeat:AZaddr2):       Started 001db01a
>  p_mysql_001    (lsb:mysql_001):        Started 001db01b
> 
> Daemon Status:
>   corosync: active/enabled
>   pacemaker: active/enabled
> 
> Here's what my constraints look like...
> 
> [root at 001db01b mysql]# pcs constraint --full
> Location Constraints:
> Ordering Constraints:
>   promote ms_drbd0 then start p_fs_clust01 (kind:Mandatory)
> (id:order-ms_drbd0-p_fs_clust01-mandatory)
>   promote ms_drbd1 then start p_fs_clust02 (kind:Mandatory)
> (id:order-ms_drbd1-p_fs_clust02-mandatory)
>   start p_fs_clust01 then start p_vip_clust01 (kind:Mandatory)
> (id:order-p_fs_clust01-p_vip_clust01-mandatory)
>   start p_vip_clust01 then start p_azip_clust01 (kind:Mandatory)
> (id:order-p_vip_clust01-p_azip_clust01-mandatory)
>   start p_fs_clust02 then start p_vip_clust02 (kind:Mandatory)
> (id:order-p_fs_clust02-p_vip_clust02-mandatory)
>   start p_vip_clust02 then start p_azip_clust02 (kind:Mandatory)
> (id:order-p_vip_clust02-p_azip_clust02-mandatory)
>   start p_vip_clust01 then start p_mysql_001 (kind:Mandatory)
> (id:order-p_vip_clust01-p_mysql_001-mandatory)
> Colocation Constraints:
>   p_azip_clust01 with p_vip_clust01 (score:INFINITY) (id:colocation-
> p_azip_clust01-p_vip_clust01-INFINITY)
>   p_fs_clust01 with ms_drbd0 (score:INFINITY) (with-rsc-role:Master)
> (id:colocation-p_fs_clust01-ms_drbd0-INFINITY)
>   p_fs_clust02 with ms_drbd1 (score:INFINITY) (with-rsc-role:Master)
> (id:colocation-p_fs_clust02-ms_drbd1-INFINITY)
>   p_vip_clust01 with p_fs_clust01 (score:INFINITY) (id:colocation-
> p_vip_clust01-p_fs_clust01-INFINITY)
>   p_vip_clust02 with p_fs_clust02 (score:INFINITY) (id:colocation-
> p_vip_clust02-p_fs_clust02-INFINITY)
>   p_azip_clust02 with p_vip_clust02 (score:INFINITY) (id:colocation-
> p_azip_clust02-p_vip_clust02-INFINITY)
>   p_mysql_001 with p_vip_clust01 (score:INFINITY) (id:colocation-
> p_mysql_001-p_vip_clust01-INFINITY)
> Ticket Constraints:
-- 
Ken Gaillot <kgaillot at redhat.com>