HP Hitachi Dynamic Link Manager Software - Manual (Page 29)

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
(sd or ssd driver). The host and storage systems are connected using SAN with fiber
cables or SCSI cables. 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 slice or 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 each physical path and manages paths on a physical-path
basis. Because you do not need to be aware of the difference between physical paths
and paths to operate HDLM, the following descriptions might simply refer to paths,
without distinguishing between physical paths and paths. The ID that HDLM assigns
to each path (physical path) is called a AutoPATH_ID. A path is also sometimes called
a managed object.
Figure 2-1: HDLM System Configuration shows the HDLM system configuration.