HP XP P9500 Storage - Manual (Page 41)

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.
When the Thunder 9500V series, or Hitachi AMS/WMS series is being used,
HDLM selects the switching destination path from owner paths and then from
non-owner paths. When the Lightning 9900 Series, Lightning 9900V Series,
Hitachi USP Series, Universal Storage Platform V/VM Series, Virtual Storage
Platform Series, Hitachi AMS2000 Series
# , Hitachi SMS Series # , HUS100
Series # , or HUS VM is being used, all paths that access the same LU are
candidates for the switching destination path.
Paths are switched in units of physical paths. Therefore, if an error occurs in a
path, all the 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 online (Places Paths Online) on page 6-11 . After
the path status is changed to online, HDLM selects the path to use in the
same way as for automatic path switching. When the Thunder 9500V series,
or Hitachi AMS/WMS series is being used, HDLM selects the path to use from
online owner paths, and then from online non-owner paths. When the
Lightning 9900 Series, Lightning 9900V Series, Hitachi USP Series, Universal
Storage Platform V/VM Series, Virtual Storage Platform Series, Hitachi
AMS2000 Series
# , Hitachi SMS Series # , HUS100 Series # , or HUS VM is being
used, because all the paths are owner paths, the path to use is not switched
even if you change the path status to online.
#
This storage system applies when the dynamic I/O path control function is
disabled.
Path Status Transition
Each of the online and offline statuses described in Performing Failovers and
Failbacks Using Path Switching on page 2-15 is further subdivided into
several statuses. The path statuses (the online path statuses and offline path
statuses) are explained below.
The Online Path Status
The online path statuses are as follows:
• Online
I/Os can be issued normally.
• Online(E)
An error has occurred in the path. Also, none of the paths that access the
same LU are in the Online status.
HDLM Functions
2-19
Hitachi Dynamic Link Manager User Guide for Solaris ®