HP LUN Configuration Manager XP Software - Manual (Page 25)

Operation 25
7. The LUN Management-LDEV Configuration window opens.
This window provides access to all LUN management operations.
Define(Offline) The disk array is not servicing I/Os-to-LUNs on
ports that are being modified. You can add or
delete paths and modify port configurations.
Define(Online) The disk array continues to service all I/Os. You
can only add new paths.
Reference The array continues to service all I/Os. No
changes are allowed. You can only view path and
port information.