HiCommand Dynamic Link Manager User's Guide (for Windows(R))

2.8.3 Actions for intermittent error monitoring

Intermittent error monitoring is performed for each path,. and it starts when a path is recovered from an error by using automatic failback.

This subsection describes the following actions for intermittent error monitoring:

When an intermittent error occurs

When an intermittent error does not occurs

When the conditions for the intermittent error are changed during error monitoring

Organization of this subsection

(1) When an intermittent error occurs

(2) When an intermittent error does not occur

(3) When the conditions for an intermittent error are changed during error monitoring

(1) When an intermittent error occurs

When an error occurs in a path the specified number of times within the specified interval, the error monitoring finishes, the path is determined to have an intermittent error, and then the path is removed from those items subject to automatic failback. The path that is removed from the paths that are subject to automatic failback has an error status until the online operation is performed properly. However, if the path satisfies certain conditions, it will be subject to automatic failback and change to online (Online). For details on the conditions, see Figure 2-11 Path status transitions.

Figure 2-12 Action when an intermittent error occurs in the path shows the action for intermittent error monitoring when an intermittent error occurs. In this example, the path is determined to have an intermittent error when the error occurs 3 or more times in 30 minutes. The event occurred in one path is described on the time arrow.

Figure 2-12 Action when an intermittent error occurs in the path

(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, an intermittent error does not occur. In this case, the error monitoring finishes when the specified error monitoring interval finishes and the number of errors is reset to 0. If an error occurs in the path later, the error monitoring resumes at the time the path is recovered from the error by using automatic failback.

If errors occur after a long interval, an intermittent error can be detected by increasing the error monitoring interval or by decreasing the number of times that the error is to occur (in order for the system to determine that an intermittent error is occurring).

Figure 2-13 Action when an intermittent error does not occur in the path shows the action for intermittent error monitoring when an intermittent error does not occur. In this example, the path is determined to have an intermittent error if the error occurs three or more times in 30 minutes. The event occurring in one path is described on the time arrow.

Figure 2-13 Action when an intermittent error does not occur in the path

The number of times that the error is to occur is counted when an error occurs. As shown in Figure 2-13 Action when an intermittent error does not occur in the path, normally the number of times that the error is to occur is counted each time an error occurs after the path is recovered online by automatic failback during intermittent error monitoring. However, if all the paths connected to the LU are in Offline(E), Online(E), or Offline(C) status due to disconnection of the paths or other reasons, the path is not recovered online by automatic failback. If I/O operations 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 is to occur 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.

(3) When the conditions for an intermittent error are changed during error monitoring

When the conditions (error monitoring interval and the number of times that the error is to occur) for an intermittent error are changed during error monitoring, the number of errors and the time that has passed since the error monitoring started are reset to 0. The error monitoring does not finish and resumes from the time the conditions are changed.

When you change the conditions outside the error monitoring time, at the time the path is recovered from the error by using automatic failback, the error monitoring starts with the changed conditions.

Figure 2-14 Action when the conditions for the intermittent error are changed during error monitoring shows the action for intermittent error monitoring when the conditions for an intermittent error are changed during error monitoring. In this example, the conditions have been changed from 3 or more errors in 30 minutes, to 3 or more errors in 40 minutes. The events occurring in one path are written on the time arrow.

Figure 2-14 Action when the conditions for the intermittent error are changed during error monitoring

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