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

HiCommand
®
Dynamic Link Manager (HDLM) for Windows
®
Systems User’s Guide 41
2.9 Detecting Errors Using Path Health Checking
HDLM can check the status of paths at regular intervals, and detect errors. This functionality
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 or the Path Management window of the HDLM GUI
to check the path error.
For example, in a normal state, I/O is not performed on the paths of the standby host in the
cluster configuration or on the non-owner paths (that is, some of the paths that access the
TagmaStore AMS/WMS series, Thunder 9500V Series, and Thunder 9200 storage system).
Because of this, for the standby host or 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 recent path-status information when selecting the switching destination.
You can configure path health checking by using the Options window of the HDLM GUI or by
executing the dlnkmgr command's set operation. For details on the Options window, see
sections
4.2.8 and 6.3. For details on the set operation, see section 7.6.