6.8. Move Resources Manually

There are always times when an administrator needs to override the cluster and force resources to move to a specific location. In this example, we will force the WebSite to move to pcmk-1.

We will use the pcs resource move command to create a temporary constraint with a score of INFINITY. While we could update our existing constraint, using move allows to easily get rid of the temporary constraint later. If desired, we could even give a lifetime for the constraint, so it would expire automatically — but we don’t that in this example.

[root@pcmk-1 ~]# pcs resource move WebSite pcmk-1
[root@pcmk-1 ~]# pcs constraint
Location Constraints:
  Resource: WebSite
    Enabled on: pcmk-1 (score:50)
    Enabled on: pcmk-1 (score:INFINITY) (role: Started)
Ordering Constraints:
  start ClusterIP then start WebSite (kind:Mandatory)
Colocation Constraints:
  WebSite with ClusterIP (score:INFINITY)
Ticket Constraints:
[root@pcmk-1 ~]# pcs status
Cluster name: mycluster
Stack: corosync
Current DC: pcmk-2 (version 1.1.18-11.el7_5.3-2b07d5c5a9) - partition with quorum
Last updated: Mon Sep 10 17:28:55 2018
Last change: Mon Sep 10 17:28:27 2018 by root via crm_resource on pcmk-1

2 nodes configured
2 resources configured

Online: [ pcmk-1 pcmk-2 ]

Full list of resources:

 ClusterIP      (ocf::heartbeat:IPaddr2):       Started pcmk-1
 WebSite        (ocf::heartbeat:apache):        Started pcmk-1

Daemon Status:
  corosync: active/disabled
  pacemaker: active/disabled
  pcsd: active/enabled

Once we’ve finished whatever activity required us to move the resources to pcmk-1 (in our case nothing), we can then allow the cluster to resume normal operation by removing the new constraint. Due to our first location constraint and our default stickiness, the resources will remain on pcmk-1.

We will use the pcs resource clear command, which removes all temporary constraints previously created by pcs resource move or pcs resource ban.

[root@pcmk-1 ~]# pcs resource clear WebSite
[root@pcmk-1 ~]# pcs constraint
Location Constraints:
  Resource: WebSite
    Enabled on: pcmk-1 (score:50)
Ordering Constraints:
  start ClusterIP then start WebSite (kind:Mandatory)
Colocation Constraints:
  WebSite with ClusterIP (score:INFINITY)
Ticket Constraints:

Note that the INFINITY location constraint is now gone. If we check the cluster status, we can also see that (as expected) the resources are still active on pcmk-1.

[root@pcmk-1 ~]# pcs status
Cluster name: mycluster
Stack: corosync
Current DC: pcmk-2 (version 1.1.18-11.el7_5.3-2b07d5c5a9) - partition with quorum
Last updated: Mon Sep 10 17:31:47 2018
Last change: Mon Sep 10 17:31:04 2018 by root via crm_resource on pcmk-1

2 nodes configured
2 resources configured

Online: [ pcmk-1 pcmk-2 ]

Full list of resources:

 ClusterIP      (ocf::heartbeat:IPaddr2):       Started pcmk-1
 WebSite        (ocf::heartbeat:apache):        Started pcmk-1

Daemon Status:
  corosync: active/disabled
  pacemaker: active/disabled
  pcsd: active/enabled

To remove the constraint with the score of 50, we would first get the constraint’s ID using pcs constraint --full, then remove it with pcs constraint remove and the ID. We won’t show those steps here, but feel free to try it on your own, with the help of the pcs man page if necessary.