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

2.7 Failover and failback using path switching

When the system contains multiple paths to an LU and an error occurs in the path being used, HDLM can switch to another normal path to allow the system to continue to operate. This functionality is called failover.

When the path in which an error occurred recovers from the error, HDLM can switch the paths so that the recovered path is used. This functionality is called failback.

Two types of failover and failback are available:

Automatic path switching

Manual path switching

Failover and failback change the path statuses and switch the paths. Path statuses are classified into online statuses and offline statuses. Online statuses allow the path to normally receive I/Os. Offline statuses prevent the path from receiving I/Os for the following reasons:

An error occurred in the path.

A user placed the path offline using the Path Management window of the HDLM GUI.

A user executed the HDLM command's offline operation.
For details on the offline operation, see 7.4 offline (Places a path or paths offline).

Hardware such as cables or HBAs is removed.

For details on path statuses and the status transitions, see 2.7.3 Path status transition.

Note

When using the Thunder 9200, Thunder 9500V Series, or TagmaStore AMS/WMS series make sure that you set the data share mode to ON (Used).

For details on the data share mode, see the manual for Thunder 9200, Thunder 9500V Series, or TagmaStore AMS/WMS series.

Organization of this section

2.7.1 Automatic path switching

2.7.2 Manual path switching

2.7.3 Path status transition

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