HP Hitachi Dynamic Link Manager Software - Manual (Page 27)

Devices Managed by HDLM
Below is a list of devices that can or cannot be managed by HDLM. The
devices that can be managed by HDLM are called HDLM management-target
devices.
HDLM management-target devices:
The following devices of the storage systems listed in Section What is
HDLM? on page 1-2 :
¢
SCSI devices
¢
Boot disks
Non-HDLM management-target devices:
¢
SCSI devices other than those of the storage systems listed in Section
What is HDLM? on page 1-2
¢
Devices other than disks (such as tape devices)
¢
Command devices of the storage systems listed in Section What is
HDLM? on page 1-2 (For example, Hitachi RAID Manager command
devices.)
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. Note that an FC-SAN and an IP-SAN cannot be combined and
connected to the same environment.
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.
HDLM Functions
2-3
Hitachi Dynamic Link Manager User Guide for Linux ®