HP Hitachi Dynamic Link Manager Software - Manual (Page 52)

2. HDLM Functions
30
2.9 Intermittent Error Monitoring (Functionality When Automatic
Failback Is Used)
An intermittent error means an error that occurs irregularly because of, for example, a
loose cable connection. I/O performance might decrease while an automatic failback
is being performed to repair an intermittent error. This is because the automatic
failback operation is being performed repeatedly (because the intermittent error keeps
occurring). To prevent this from happening, HDLM can automatically remove the path
where an intermittent error is occurring from the paths that are subject to automatic
failbacks. This process is called intermittent error monitoring.
We recommend that you use intermittent error monitoring along with the automatic
failback function.
A path in which an error occurs a specified number of times within a specified interval
is determined to have an intermittent error. The path where an intermittent error occurs
has an error status until the user chooses to place the path back online. Automatic
failbacks are not performed for such paths. This status is referred to as the not subject
to auto failback status.
2.9.1 Checking Intermittent Errors
You can check the paths in which intermittent errors have occurred by viewing the
execution results of the HDLM command's
view
operation.
For details on the
view
operation, see 6.7 view (Displays Information).
2.9.2 Setting Up Intermittent Error Monitoring
When you use the intermittent error function, you can enable or disable the function.
If you enable the function, specify the monitoring conditions: the error monitoring
interval, and the number of times that the error is to occur. If an error occurs in a path
the specified number of times within the specified error monitoring interval, the
system determines that the path has an intermittent error. For example, if you specify
30 for the error monitoring interval and 3 for the number of times that the error is to
occur, the path is determined to have an intermittent error if an error occurs 3 or more
times in 30 minutes.
You can set up intermittent error monitoring by executing the
dlnkmgr
command's
set
operation.
Intermittent error monitoring can be used only when automatic failback has already
been enabled. The values that can be specified for intermittent error monitoring depend
on the values specified for automatic failbacks. For details on how to specify the
settings, see 6.6 set (Sets Up the Operating Environment).