HP Hitachi Dynamic Link Manager Software - Manual (Page 31)

2. HDLM Functions
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2.2 System Configuration
HDLM manages routes between a host and a storage system by using the SCSI driver.
A host and a storage system are connected via an FC-SAN or an IP-SAN.
2.2.1 System Configuration Using an FC-SAN
In an FC-SAN, fiber cables connect hosts to storage systems. The cable port on the
host is a host bus adapter (HBA). The cable port on the storage system is a port (P) on
a channel adapter (CHA).
A logical unit (LU) contained in a storage system is the target of input to, or output
from, the host. You can divide an LU into multiple areas. Each area after the division
is called a Dev. The Dev is equivalent to a partition. A route that connects a host and
an LU is called a physical path, and a route that connects a host and a Dev is called a
path. When an LU has been divided into multiple Devs, the number of paths set to the
LU is equal to the number that is found by multiplying the number of physical paths
by the number of Devs in the LU.
HDLM assigns an ID to a physical path and manages the paths on a physical-path
basis. When you use HDLM, there is no need to consider the difference between a
physical path and a path. Thus, hereafter both physical paths and paths might be called
paths, without a distinction being made between the two. The ID that HDLM assigns
for each physical path is called an AutoPATH_ID. Also, a path might be called a
management target.
Figure 2-1: Configuration of an HDLM System When Using an FC-SAN shows the
configuration of an HDLM system using an FC-SAN.