HP XP7 Storage - Manual (Page 40)

change the paths to the blocked state (Offline(C)) before you change the
intermittent error monitoring setting.
You can check whether intermittent error monitoring is being performed for a
path, by executing the HDLM command's view -path operation with the -iem
parameter specified, and then checking the displayed IEP item. If a numerical
value of 0 or greater is displayed for this item, intermittent error monitoring
is being performed on the path.
For details about the view operation, see view (Displays Information) on page
6-25 .
Detecting Errors by Using Path Health Checking
HDLM can check the status of paths for which I/O operations are not being
performed and detect errors. This function is called path health checking.
The path health check function periodically checks the status of online paths
regardless of whether any I/O activity is occurring. If an error is detected in a
path, the path health checking function switches the status of that path to
Offline(E). You can use the dlnkmgr command's view operation to check
the path error.
The health check function is implemented by functionality provided by
VMware vSphere ESXi. You cannot disable the health check function or
change the interval between checks.
Distributing a Load by Using the Dynamic I/O Path Control
Function
The result of using HDLM load balancing to distribute a load can be improved,
by applying the HDLM dynamic I/O path control function to the storage
system in which the dynamic load balance control function is installed.
What is the Dynamic Load Balance Control Function
In a system configuration in which multiple hosts and a storage system are
connected, the I/O processing load tends to concentrate on the controller of
the storage system, causing throughput performance of the entire system
decrease. The dynamic load balance controller function evaluates such load
statuses on the controller and prevents storage system performance from
decreasing.
The following is a list of the storage systems that provide the dynamic load
balance controller function and are supported by HDLM.
• Hitachi AMS2000 series #
• Hitachi SMS series #
• HUS100 series
2-22
HDLM Functions
Hitachi Dynamic Link Manager (for VMware®) User Guide