HP Hitachi Dynamic Link Manager Software - Manual (Page 54)

2. HDLM Functions
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2.8 Monitoring intermittent errors (functionality when automatic
failback is used)
An intermittent error refers to an error that occurs irregularly because of something
like a loose cable. In such a case, 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. Failbacks are
not performed for such paths. This status is referred to as the not subject to auto
failback status.
2.8.1 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).
2.8.2 Setting up intermittent error monitoring
When you enable the intermittent error monitoring function, specify the following
monitoring conditions: the error monitoring interval, and the number of times that the
error needs to occur. If an error occurs on a particular path the specified number of
times within the specified error-monitoring interval, then an intermittent error will
occur on the path. For example, if you specify 30 for the error monitoring interval and
3 for the number of times that the error needs 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).