In fact, this link seems to be almost what I want to do:
https://clusterlabs.org/pacemaker/doc/en-US/Pacemaker/1.1/html/Clusters_from_Scratch/_configure_the_cluster_for_drbd.html
The only missing parts are:
1. Avoid node3 and node4.
2. Preferentially run on node1 when it becomes active again.
What is the pcs command to achieve those?
On Tue, 11 May 2021, Andrei Borzenkov wrote:
[EXTERNAL EMAIL]
On 10.05.2021 20:36, Alastair Basden wrote:
Hi Andrei,
Thanks. So, in summary, I need to:
pcs resource create resourcedrbd0 ocf:linbit:drbd drbd_resource=disk0 op
monitor interval=60s
pcs resource master resourcedrbd0Clone resourcedrbd0 master-max=1
master-node-max=1 clone-max=2 clone-node-max=1 notify=true
pcs constraint location resourcedrb0Clone prefers node1=100
pcs constraint location resourcedrb0Clone prefers node2=50
pcs constraint location resourcedrb0Clone avoids node3
pcs constraint location resourcedrb0Clone avoids node4
Does this mean that it will prefer to run as master on node1, and slave
on node2?
No. I already told you so.
If not, how can I achieve that?
DRBD resource agents sets master scores based on disk state. If you
statically override this decision you are risking promoting stale copy
which means data loss (I do not know if agent allows it, hopefully not;
but then it will continue to attempt to promote wrong copy and
eventually fail). But if you insist, it is documented:
https://clusterlabs.org/pacemaker/doc/en-US/Pacemaker/2.0/html/Pacemaker_Explained/s-promotion-scores.html
Also statically biasing one single node means workload will be relocated
every time node becomes available, which usually implies additional
downtime. That is something normally avoided (which is why resource
stickiness exists).
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