Submit a ticketCall us

AnnouncementsAre You “Flying Blind?”

When it comes to your complex IT infrastructure, you want to ensure you have a good grasp of what’s going on to avoid any fire drills that result from guesswork. Read our white paper to learn how proactively monitoring your IT environment can help your organization while giving you peace of mind.

Get your free white paper.

Home > Success Center > Network Performance Monitor (NPM) > NPM - Knowledgebase Articles > SNMP returns a negative value when polling huge disk space on Windows

SNMP returns a negative value when polling huge disk space on Windows

Updated December 13, 2016


When polling the value for disk size (hrStorageSize), the value returns as negative. This happen because the counter overruns.

This issue should be presented to the vendor.


  • All NPM versions
  • Windows



  1. In UnDP, create a New Universal Device Poller.
  2. Search the OID for hrStorageSize . (where 'x' is the disk number on the MIB branch).
  3. Select MIB Value Type: Counter.
  4. SNMP Get Type: GET.
  5. Polling Type: Node.
  6. Polling Interval: 10m.
  7. Keep Historical Data: yes.
  8. Status: Enabled.
  9. Create a 'Transform Results'
  10. Define the Transform (the Polling Interval should be the same of the UDP before: 10m)
  11. The formula:
    1. ('Int32-MaxValue'*2)-(-('SnmpNegativeReturn)))*AllocationUnits
    2. Int32-MaxValue - Max Value in a 32bit variable
    3. SnmpNegativeReturn - the OID that is returning a negative value
    4. AllocationUnits  - Size of the block allocation in the disk

Example: ((2147483647*2)-(-(-1366779137)))*4096 =11993858691072




Last modified