Hard disk space is not reporting correctly for very large hard drive volumes

Products

• VMware Smart Assurance

Issue/Introduction

Symptoms:

Hard drive volume sizes are calculated incorrectly for some volumes on Windows servers that have been discovered into Smarts IP Manager.

Environment

Smarts - 10.1.x / 2.x
TCSA - 2.x

Cause

Smarts uses a calculation to determine the size of a hard disk partition based on specific values that are collected from SNMP.  
Smarts multiplies the number of allocation units by the size of the allocation unit.  

The problem arises from the SNMP MIB that stores the value for the number of allocation units.  

• The default SNMP agent that is used for Windows only uses a 32-bit integer to store the number of allocation units.  
• This means that the calculation is only valid up to a maximum of 2,147,483,647 allocation units in a volume.  
• With the size of volumes that are now available and the relatively small default allocation unit size, it has become more and more common to have volumes that exceed the maximum value of a 32-bit integer.

Resolution

Unfortunately, there is no work around currently for this issue.  This is a limitation of the SNMP agent used on these devices.  Smarts cannot provide a work around for a value in SNMP that places an incorrect value in this field.