It’s not uncommon in Pacemaker clusters to run specific cron jobs only on a node that currently runs a particular resource. The ocf:heartbeat:symlink resource agent can be exceptionally helpful in this situation. Here’s how to use it.

Suppose you’ve got a cron job for Postfix …

Occasionally, you may see errors similar to this in your system logs:

corosync [TOTEM ] Retransmit List: e4 e5 e7 e8 ea eb ed ee

Here’s what causes them, and what you can do to fix the issue.

Corosync, more specifically its Totem protocol implementation, defines a maximum number of …

Ever wanted to know just which of your OSDs a RADOS object is currently stored in? Here’s how.

Suppose you’ve got an RBD device, named test. Then you can use the rbd info command to display which name prefix is used by the RADOS objects that make up …

Whenever a DRBD setup runs into a situation where the replication network is disconnected and fencing policy is set to dont-care (default), there is the potential risk of a split-brain. Even with resource level fencing or STONITH setup, there are corner cases that will end up in a split-brain.

When …

It’s simple and easy to get Pacemaker’s view of the status of members in a cluster – just invoke crm_mon. But what if you want to check on the cluster membership when Pacemaker is not running, or you want to make sure whether Corosync’s view of the cluster …