Hitachi Dynamic Link Manager Software Users Guide for AIX (6.6) (T5208-96010, April 2011)

2. HDLM Functions

2.9 Detecting errors by using path health checking

HDLM can check the status of paths for which I/O operations are not being performed

at regular intervals. This function is called path health checking.

Without path health checking, an error is not detected unless I/O is performed because

the system only checks the path status when I/O is performed. With path health

checking, however, the system checks the status of online paths at regular intervals

regardless of whether I/O is performed. If an error is detected in a path, path health

checking functionality switches the status of that path to

Offline(E) or Online(E),

so you can use the

dlnkmgr command's view operation to check the path error.

For example, in a normal state, I/O operations are not performed on the paths coming

from the standby host in the cluster configuration or on non-owner paths (that is, some

of the paths that access a Thunder 9500V series and Hitachi AMS/WMS series storage

system). Because of this, for the standby host or for a host connected to non-owner

paths, we recommend that you use path health checking to detect errors. This enables

the system to use the most up-to-date path-status information when selecting the next

path to use.

You can configure path health checking by executing the

dlnkmgr command's set

operation. For details on the

set operation, see 6.6 set (Sets Up the Operating

Environment).