HP Hitachi Dynamic Link Manager Software - Manual (Page 50)

The number of errors and the time passed since error monitoring had
started are both reset to 0, and then monitoring restarts from the time
the HDLM manager starts.
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 cannot be detected unless an I/O
operation is performed, because the system only checks the status of a path
when an I/O operation is performed. With path health checking, however, the
system can check the status of all online paths at regular intervals regardless
of whether I/Os operations are being performed. If an error is detected in a
path, the path health checking function switches the status of that path to
Offline(E) or Online(E). 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 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
or 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 using the Options window of the
HDLM GUI or by executing the dlnkmgr command's set operation. For details
on the Options window, see the HDLM GUI Help. For details on the set
operation, see set (Sets Up the Operating Environment) on page 6-15 .
Dynamic Re-configuration
Utilizing the Windows plug-and-play functionality, you can add or delete an
LU or a path while the host (on which HDLM is installed) is still running. This
is called the dynamic re-configuration function. For details on the dynamic re-
configuration function, see Setting Up an Added LU and Path as an HDLM
Management-target on page 4-16 .
Adding an LU Dynamically
The function to dynamically add an LU enables you to add an LU or a path
while a host (on which HDLM is installed) is running.
For details on the LU dynamic addition function, see Setting Up an Added LU
and Path as an HDLM Management-target on page 4-16 .
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HDLM Functions
Hitachi Dynamic Link Manager User Guide (for Windows(R))