As volumes larger than 16TB became more common, it was recognized that the 32 bit value used to report disk size and usage within the standard "HOST-RESOURCES" MIB in SNMP was not large enough to report the proper disk size.

Net-SNMP seems to have addressed this issue by simply manipulating the value of "AllocationUnits" to maintain a 32 bit value for disk utilization (since total disk size/usage is equal to the 32 bit space value times the allocation unit), to allow for the calculation of a volume larger than 8/16TB. Presuming you don't have any reporting interest in the allocation unit, this seems like a fine solution.

https://bugzilla.redhat.com/show_bug.cgi?id=654384

Window's built in SNMP service, however, seems to continue to suffer from this error, simply reporting the modulo of the used/assigned disk space, resulting in inaccurate disk size reporting.

Is there a way to enable Windows to correctly report disk usage for volumes over 16TB? We attempted to simply install Net-SNMP 5.5 x64 and disable Windows SNMP service entirely, however this unfortunately did not fix our issue.

I've seen people in the Cacti community mention simply scripting out a solution. Unfortunately, we're using Observium for quick and basic systems monitoring. If the issue can't be correct on the Window's side, can Observium be made to report custom MIBs?