You can switch the status of a path by manually placing the path online or offline. Manually switching a path is useful, for example, when system maintenance needs to be done.
You can manually place a path online or offline by doing the following:
Execute the dlnkmgr command's online or offline operation.
For details on the online operation, see online (places paths online). For details on the offline operation, see offline (places paths offline).
However, if there is only one online path for a particular LU, that path cannot be manually switched offline. Also, a path with an error that has not been recovered from yet cannot be switched online.
HDLM uses the same algorithms to select the path that will be used next, regardless of whether automatic or manual path switching is used.
In a normal state, all paths that access the same LU are candidates for the switching destination path. However, if non-owner paths exist, HDLM selects the switching destination path from the owner paths and then from the non-owner paths.
Executing the online operation places the offline path online. For details on the online operation, see online (places paths online). If non-owner paths are also used, HDLM selects the path to use from the online owner paths, and then from the online non-owner paths.