Just a quick one as i had to spend a while searching for an answer as this isn’t really written anywhere in black and white.
Was working on a support case the other day where the customer had reported that the disks for their clusters were not monitored. After looking into this i could see that the logical disks were not monitored but the cluster disks were.
After plenty of digging i managed to find an old article from Kevin Holman who is an authority on SCOM confirming that logical disks are not discovered for clusters, rather, the cluster disks are discovered as a different class. The link is here: https://blogs.technet.microsoft.com/kevinholman/2012/06/14/opsmgr-mp-update-new-base-os-mp-6-0-6972-0-adds-new-cluster-disks-changes-free-space-monitoring-other-fixes/
May seem like an obvious thing, but if you haven’t really ever noticed or had to work with monitoring cluster disks then its something you may overlook.
Happily i could go back to the customer with an easy fix though… It’s meant to do that!