With RH 6.6 and 6.7 (I've not tried earlier) I've found that putting

realStorageUnits 0

in snmpd.conf (and obviously restarting the daemon) appears to provide a fix.

It's noted in bug BZ#654384 https://bugzilla.redhat.com/show_bug.cgi?id=654384 here:

https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/5/htm...

It may be worth amending the FAQ ?