HP Hitachi Dynamic Link Manager Software User Manual

Page 54

2. HDLM Functions

(2) When an Intermittent Error Does Not Occur

If an error does not occur in the path the specified number of times within the specified

interval, the system determines that the path does not have an intermittent error. 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.
Figure 2-11: What Will Happen When an Intermittent Error Does Not Occur on a

Path shows what will happen when an intermittent error does not occur. 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 2-11: What Will Happen When an Intermittent Error Does Not Occur on

a Path

As shown in Figure 2-11: What Will Happen When an Intermittent Error Does Not

Occur on a Path, 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 are continuously issued to such a LU, the number

of times that the error is to occur might be counted even if the path is not 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,