In our clustered environments, instances are given a small drive for mounting the larger data/log/etc volumes within them.
Whilst we always get a "disk full" warning on the mountpoint drives (subsequently disabled), there appears to be no ability to monitor the volumes that are mounted within, where we do care about free space.
I do see that metrics for IO, latency etc are done on a per volume (not drive letter) basis, so would be great if we could have consistency.