HP Hitachi Dynamic Link Manager Software - Manual (Page 140)

124 Chapter 4 HDLM Operation
4.1 Notes on Using HDLM
This section provides notes on HDLM operation.
4.1.1 Using a Storage Management Program
You must not change the vendor and product IDs of the storage system. If you change them,
HDLM cannot recognize the storage system.
4.1.2 Upgrading Windows
Before upgrading the OS from Windows 2000 Server to Windows Server 2003 or re-installing
the OS during system recovery, always uninstall HDLM. After upgrading the OS, install the
appropriate HDLM version for the upgraded OS.
4.1.3 Using MSCS
4.1.3.1 When the Number of Displayed Paths is Less Than the Actual Number of Paths
When displaying path information, the number of paths displayed might be less than the
actual number of paths. This occurs when one host uses an LU exclusively, preventing other
hosts from obtaining information about the devices in that LU. When this is resolved and the
information can be obtained, the host can display all paths.
4.1.3.2 When a System Event Occurs in the MSCS Environment
When you start a standby node, or when a standby node has recovered from a path error,
the following event is issued and output to the system event log. However, you can still
perform operations as usual.
Source: mpio
Event ID: 20
Description: A Path Verification request to a device on \Device\MPIODiskn that is
controlled by Hdlm Device-Specific Module has failed. This may indicate a Path Failure.
This event occurs when MPIO checks the disk before initializing it and the standby node
cannot use the LU because the active node is using it.