Use snmpGet to get size of storage allocation unit for storageSystem. Pass device parameters for snmp and filesystem snmpindex to get correct OID instance.

snmpGetHrStorageAllocationUnits.sh

#!/bin/sh
# Driven by
# /z/scripts/snmpGetHrStorageAllocationUnits.sh ${device/manageIp} ${device/zSnmpCommunity} ${device/zSnmpVer} ${here/snmpindex}

set -x
# Nagios return codes
STATE_OK=0
STATE_WARNING=1
STATE_CRITICAL=2
STATE_UNKNOWN=3
#
exitstatus=$STATE_OK

# Nagios format echos information and status followed by pipe |
#  followed by <var name>=<value> tuples
# Note that Zenoss datapoints must match these var names exactly
#
#echo $1 $2 $3 $4
#  1.3.6.1.2.1.25.2.3.1.4 is the OID for the host resources storage mib for blockSize - hrStorageAllocationUnits
#  The snmpget needs to add the instance for each filesystem instance - this comes from the snmpindex attribute
#   which is passed in the 4th parameter to the script
blockSize=$(/usr/bin/snmpget -$3 -c $2  -O qvU  $1 1.3.6.1.2.1.25.2.3.1.4.$4 2>&1 | cut -f 1 -d " ")
# Response is:
#   <number> Bytes                                      to stdout
#  No Such Instance currently exists at this OID        to stdout
#  Timeout: No Response from <ip>                       to stderr
# Use cut to get the first space-separated field
#
#Next line tests whether result is a number; if so then snmpget successful
if [ "$blockSize" -eq "$blockSize" ] 2>/dev/null
then
    echo "Block size test - status OK | blockSize=$blockSize"
    exit $exitstatus
elif [ "$blockSize" == "No" ]
then echo "Block size test failed -no such OID"
     exitstatus=$STATE_CRITICAL
     exit $exitstatus
elif
    [ "$blockSize" == "Timeout:" ]
then echo "Block size test failed - no response"
     exitstatus=$STATE_CRITICAL
     exit $exitstatus
else
     echo "Block size test failed -unknown error"
     exitstatus=$STATE_UNKNOWN
     exit $exitstatus
fi