HP SureStore E SAN Manager LUN Management Administrator's Guide

A SAN Manager LM Device Cannot Be Unassigned 195
Troubleshooting
Tip If you need help discovering why a device cannot be unassigned, the following
third-party utilities from Sysinternals may be helpful: Handle for Windows NT
and HandleEx for Windows NT.
HP is not responsible for any errors that might arise from using this third-party
software.
A service or SNMP agent is preventing the device unassignment.
Services are configurable under the Services control panel and SNMP
agents are loaded by the SNMP service. Disable unneeded
storage-related services and SNMP agents. If a needed service or agent
is causing the problem, shut down the node to unassign devices.
Symptom Cause/Solution