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HP Hitachi Dynamic Link Manager Software User Manual

Page 52

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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).