Up until 8pm last night, we were monitoring a server using SNMP Disk Free sensors. At that time the machine was rebooted and now we're seeing errors for all but C and D drive (others are E, F, G, H, I, J, and Q).
The error message is the same for all, "Could not find data for E:\ Label:Data Serial Number e8becf36", though the label and serial numbers differ of course.
When I try to add a new sensor of that type, only the C and D drives show up as possibilities.
It has a large number of other sensors which still work (ping, uptime, various ethernet and LAN ones, CPU, physical and virtual memory and so on) though I have no idea which of these are SNMP. The thing that's got me is that C and D still work and they're the same sensor type.
What could be causing this? Is Windows able to somehow hide disks from SNMP?