HiCommand Dynamic Link Manager (HDLM) for Windows Systems User's Guide (HIT5201-96001, January 2008)

4 Chapter 1 Overview of HDLM
1.2 HDLM Features
HDLM provides the following features:
Distributes the load across paths (load balancing)
When multiple paths connect a host and storage system, HDLM distributes the load
across the paths. This prevents a heavily loaded path from affecting processing speed.
For details on load balancing, see section
2.6.
Allows processing to continue if there is a failure (failover)
When multiple paths connect a host and storage system, HDLM automatically switches to
another path if there is a failure in a path being used. This allows processing to continue
without being affected by the failure.
For details on failover, see section
2.7.
Allows you to place online a path recovered from an error (failback)
When a path recovers from an error, HDLM can place the path online. This enables the
maximum number of paths to be online, which in turn enables HDLM to distribute the
load for each path.
Route failbacks can be performed manually or automatically. In an automatic failback,
HDLM automatically restores the route to the active state after the user has corrected
the problem in the physical route.
For details on failback, see section
2.7.
Automatically checks the path status at regular intervals (path health checking)
HDLM can detect errors by checking the status of the paths at user-defined time
intervals. This allows you to check for any existing path errors and to resolve them
accordingly.
For details on path health checking, see section
2.9.
Allows you to use a GUI to operate HDLM visually (HDLM GUI)
HDLM uses a configuration-diagram or list format to display information about paths
between hosts and Hitachi storage systems. You can use the GUI to change the status of
a path, and to set the operating environment.
For details on the HDLM GUI, see sections
4.2 and 6.1.