Status transitions of a path

The following figure shows the status transitions of a path.

Legend:

Online operation: Online operation performed by executing the dlnkmgr command's online operation.

Offline operation: Offline operation performed by executing the dlnkmgr command's offline operation.

#1

In the following cases, if the processing of continuous I/O operations issued to the LU is successful, the status of the path changes from Online(E) to Online:

• The automatic failback function is disabled.

• The automatic failback function is enabled, and the path has been determined to have an intermittent error.

#2

When an Online or Offline(E) path exists among the paths that access the same LU.

#3

The path status changes when I/O is issued to a path where a failure has occurred.

#4

The path status changes when I/O is issued to a path where a failure has occurred or when HDLM detects a path failure during path health checking. For details on path health checking, see Detecting errors by using path health checking.

If there is only one available online path for an LU, it cannot be placed offline by executing the offline operation. This ensures that the LU can always be accessed by at least one path. For details on the offline operation, see offline (places paths offline).

If none of the paths accessing a particular LU are in the Online status, one of the paths is changed to the Online(E) status. If you are using the automatic failback function, after the path has recovered from the error, the path in the Online(E) status is automatically changed to the Online status. Note that when you are using intermittent error monitoring, the path in which the intermittent error occurred is not automatically placed in the Online status when the path recovers from the error. In such a case, place the path in the Online status manually.

Note

If there is a path failure immediately after a path is taken offline by using either the an HDLM command, the status might change from Offline(C) to Offline(E). If an offline operation was just performed, wait about 1 minutes, check the path status by using an HDLM command, and then make sure that the status has changed to Offline(C). If it is still Offline(E), retry the offline operation.