Hitachi Dynamic Link Manager Software Users Guide for AIX (6.6) (T5208-96010, April 2011)

2. HDLM Functions
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other paths that run through the same physical path are switched.
Executing the
online operation places the offline path online. For details on the
online operation, see 6.5 online (Places Paths Online). After the path status is
changed to online (by executing the
online operation), HDLM selects the path to use
in the same way as for automatic path switching. When using the Thunder 9500V
series, or Hitachi AMS/WMS series, HDLM selects the path to use from online owner
paths, and then from online non-owner paths. When the Lightning 9900V series,
Hitachi USP, Universal Storage Platform V/VM, Virtual Storage Platform, Hitachi
AMS2000 series, or Hitachi SMS is being used, since all the paths are owner paths, the
path to use is not switched even if you change the path status to online by using the
online operation.
2.7.3 Path status transition
Each of the online and offline statuses described in 2.7 Performing Failovers and
Failbacks Using Path Switching is further subdivided into two statuses. The following
explains the two online path statuses and the two offline statuses.
(1) The online path status
The online path statuses are as follows:
•
Online
I/Os can be issued normally.
•
Online(E)
An error has occurred on the path, but none of the other paths that access the same
LU are in the
Online status.
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. This ensures that the LU can be
accessed through at least one path.
The (E) means error, which indicates that an error has occurred on the path from
some previous operation.
(2) The offline path status
The offline path statuses are as follows:
•
Offline(C)
The status in which I/O cannot be issued because the offline operation was
executed. For details on the
offline operation, see 6.4 offline (Places Paths
Offline).
The (C) indicates the command attribute, which indicates that the path was placed
offline by using the command.