Regarding MS perfmib.mib ...

Look for a file called permib.ini.  It will (should) be in the SYSTEM32
directory.  PERF2MIB.EXE will create it (while it creates perfmib.mib), and
it has an easier read to it.

Simply start at 1.3.6.1.4.1.311.1.1.3.1.1.

Then, for example if perfmib.ini says:
snip
5.1.1 logicalDisk\*
5.1.2 logicalDisk\Instance Name
5.1.3 logicalDisk\% Free Space
5.1.4 logicalDisk\Free Megabytes
snip
... and you want to get free megabytes remaining on either drive, then the
full OID is 1.3.6.1.4.1.311.1.1.3.1.1.5.1.4.0

HOWEVER... if you have more than one drive and/or partitions, then you will
need to walk the OID tree (I use SNMPUTIL.EXE from the NT Reskit)to get the
further disk qualifications.

----------------------------------------------------------------------------
-----------------
SNMPUTIL WALK #1
----------------------------------------------------------------------------
-----------------
U:\>snmputil walk 127.0.0.1 cilbup .1.3.6.1.4.1.311.1.1.3.1.1.5.1.
Variable = .iso.3.6.1.4.1.311.1.1.3.1.1.5.1.1.6.48.58.48.58.67.58
Value    = OCTET STRING - 0:0:C:

Variable = .iso.3.6.1.4.1.311.1.1.3.1.1.5.1.1.6.48.58.48.58.68.58
Value    = OCTET STRING - 0:0:D:

Variable =
.iso.3.6.1.4.1.311.1.1.3.1.1.5.1.1.13.95.84.111.116.97.108.58.95.84.1
11.116.97.108
Value    = OCTET STRING - _Total:_Total

U:\>
----------------------------------------------------------------------------
-------------------
As you can see I have two disk drives.  In this case they created from the
same physical disk.

Then, running snmputil walk 127.0.0.1 public
.1.3.6.1.4.1.311.1.1.3.1.1.5.1.4.
should dump a list of the drives free megabytes space and the total.
----------------------------------------------------------------------------
-----------------
SNMPUTIL WALK #2
----------------------------------------------------------------------------
-----------------
U:\>snmputil walk 127.0.0.1 cilbup .1.3.6.1.4.1.311.1.1.3.1.1.5.1.4.
Variable = .iso.3.6.1.4.1.311.1.1.3.1.1.5.1.4.6.48.58.48.58.67.58
Value    = INTEGER - 568

Variable = .iso.3.6.1.4.1.311.1.1.3.1.1.5.1.4.6.48.58.48.58.68.58
Value    = INTEGER - 91

Variable =
.iso.3.6.1.4.1.311.1.1.3.1.1.5.1.4.13.95.84.111.116.97.108.58.95.84.1
11.116.97.108
Value    = INTEGER - 659

End of MIB subtree.

U:\>
----------------------------------------------------------------------------
-------------------
To close out this message, you then can see that the full OID for free disk
remaining are as follows:

Drive C: = 1.3.6.1.4.1.311.1.1.3.1.1.5.1.4.6.48.58.48.58.67.58
(the last 7 numerics (6.48.58.48.58.67.58) match the ones retrieved in
SNMUPTIL WALK #1)

Drive D: = 1.3.6.1.4.1.311.1.1.3.1.1.5.1.4.6.48.58.48.58.68.58
(the last 7 numerics (6.48.58.48.58.68.58) match the ones retrieved in
SNMPUTIL WALK #2)

Total Free Disk Space: =
1.3.6.1.4.1.311.1.1.3.1.1.5.1.4.13.95.84.111.116.97.108.58.95.84.1.11.116.97
.108


Sorry if this message is a bit long winded, but I hope it helps others with
multiple disks and partitions!

Garth