Comment 1 for bug 1871276

I think it would be reasonable for the charm to go into a block state if the wal and db configuration options are populated, but the devices don't actually exist on the unit being used.

This would avoid just the block device part being created and used for the OSD.

As these options are whitelists its possible you won't get an exact device match for every device, but we could at least do a >= 1 of type check to validate this.