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

When an Intermittent Error Does Not Occur
If an error does not occur on a path a specified number of times within a
specified interval, an intermittent error will not occur. In such a case, the
error monitoring will finish when the specified error-monitoring interval
finishes, upon which the number of errors is reset to 0. If an error occurs on
the path again at a later time, error monitoring will resume when the path is
recovered from the error via an automatic failback.
If it takes a long time for an error to occur, an intermittent error can be more
easily detected by increasing the error-monitoring interval or by decreasing
the number of times that the error needs to occur.
The figure below shows the action taken when an intermittent error is
assumed not to have occurred on the path. For this example, the path is
determined to have an intermittent error if the error occurs three or more
times in 30 minutes. The events that occur are described by using the time
arrows.
Figure 2-14 What Will Happen When an Intermittent Error Does Not Occur
on a Path
As shown in Figure 2-14 What Will Happen When an Intermittent Error Does
Not Occur on a Path on page 2-28 , normally, the count for the number of
times that an error occurs is started after the path is first recovered from an
error by using the automatic failback function. However, if all the paths
connected to the LU are in the Offline(E), Online(E), or Offline(C) status
(which is due to the disconnection of the paths or some other reason), the
paths will not be recovered and put back online by using the automatic
failback function. If I/O operations are continuously being issued to such an
LU, the count for the number of times that the error occurs might be started
even though the path will not be placed online. If the number of times that
the error occurs reaches the specified value, the path is determined to have
an intermittent error. In such a case, remove the cause of the error, and then
manually place the path online.
When the Conditions for an Intermittent Error Are Changed During Error
Monitoring
When the conditions for an intermittent error are changed during error
monitoring, the number of errors and the amount of time that has passed
2-28
HDLM Functions
Hitachi Dynamic Link Manager User Guide for Linux ®