Hitachi Dynamic Link Manager, User Manual, Page: 62 / 746

2. HDLM Functions
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2.10 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 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) .