HP Hitachi Dynamic Link Manager Software - Manual (Page 36)

2. HDLM Functions
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2.3 LU Configuration
After you have properly installed HDLM, the LU configuration will change as follows:
Before the installation of HDLM:
The host recognizes that a SCSI device is connected to each path.
Thus, a single LU in the storage system is recognized as though there are as many
LUs as there are paths.
After the installation of HDLM:
An HDLM device corresponding one-to-one with an LU in the storage system is
created at a level higher than the SCSI device.
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Thus, from the host, LUs in the storage system are also recognized as a single LU
regardless of the number of paths.
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In addition to the one that indicates the entire LU, a logical device file for the
HDLM device is created for each partition.
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 (partition) in a storage system LU are
called host devices (HDev).
On a system using HDLM, the logical device file for the HDLM device is used to
access the target LU instead of the logical device file for the SCSI device.
Figure 2-3: LU Configuration Recognized by the Host After HDLM Installation
shows the LU configuration recognized by the host after HDLM installation.