On 2/21/20 10:51 PM, Ricardo Esteves wrote:
Hi,
I'm trying to understand what is the objective of the constraints to
have the fencing devices running on opposite node or on its own node or
running all on the same node. Can you explain the difference?
Hi Ricardo,
Using the constraints you can have a better monitoring of the IPMI
device readiness. If the 'monitor' of fence device fails then most
probably that device will be not able to fence node when needed.
Constraints for fence devices are not required by pacemaker and
pacemaker should be able to fence the nodes without them (if fence
devices are configured properly).
A) Having IPMI device of nodeX monitored from nodeY gives you following
check: 'nodeY can communicate with nodeX IPMI device and check its
status'. If in the future the nodeY would need to fence nodeX then it
should be able to connect to IPMI device.
B) Having IPMI device of nodeX monitored from nodeX gives you following
check: 'nodeX can communicate with nodeX IPMI device and check its
status'. nodeX should not fence itself for reasons mentioned in my
previous email and also in Dan's response to this. So this monitoring
doesn't provides you with useful information for future fencing. It is
not required that nodeX can communicate to nodeX IPMI device for fencing.
Most important is that fencing works for both nodes when properly
tested. Ideally try if fencing works properly. Optionally if you want
cluster to monitor IPMI devices from node that will be using them you
can use constraints to move fence devices to opposite node.
--
Ondrej Famera
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