HiCommand Dynamic Link Manager User's Guide (for Windows(R))

2.3 LU configuration

When you install HDLM, the LU configuration recognized by the host changes as follows:

Before installing HDLM:

In the disk management window of the host, a SCSI device is displayed for each path.

This means a single LU in the storage subsystem is recognized as the number of LUs that correspond to the number of paths.

After installing HDLM:

The MPIO driver integrates the LUs that are recognized for each path. In the disk management window of the host, the disk corresponding one-to-one with an LU in the storage subsystem is displayed.

This means, from the host, LUs in the storage subsystem are recognized as only one LU regardless of the number of paths.

In Windows, you can display the SCSI device in the Device Manager windows.

An LU recognized by a host after HDLM installation, is called a host LU (HLU). The areas in a host LU that correspond to the Dev in a storage subsystem LU are called host devices (HDev).

On a system using HDLM, to access the target LU, a drive letter is assigned to the disk integrated by the MPIO driver (the disk displayed in the disk management window of Windows).

Figure 2-4 LU configuration recognized by the host after HDLM installation shows the LU configuration recognized by the host after HDLM installation.

Figure 2-4 LU configuration recognized by the host after HDLM installation

Table 2-3 Components recognized by the host lists the components recognized by the host.

Table 2-3 Components recognized by the host

Components	Description
HLU	An LU that the host recognizes via the HDLM driver. It is called a host LU. Regardless of how many paths exist, only one host LU is recognized for the LU in the storage subsystem.
HDev	A Dev in an LU that the host recognizes via the HDLM driver. It is called a host device.

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