+# SAS-Switch Mode
+# -------------------------
+# When the host accesses disk via SAS switches the combination of
+# bus and port number does not necessarily uniquely identify a
+# channel or disk drawer. In this case we must resort to other
+# means to infer the physical topology. For a single-level network
+# (i.e. no switch cascading) we can assign alphabetic channel labels
+# based on the switch port number that the drawer is connected to.
+# If support for more complex topologies is needed this script will
+# need to be customized or replaced.
+#
+# In SAS-Switch mode (enabled with "-g switch" ) we require that
+# udev has been configured to create per-disk symbolic links in
+# /dev/disk/by-id of the form
+# <label>-<UUID>-switch-port:<X>-slot:<Y>. <label> is a string that
+# depends on the subsystem that created the link and defaults to
+# "dm-uuid-mpath" (this prefix is used by multipathd). <UUID> is a
+# unique identifier for the disk typically obtained from the scsi_id
+# program. <X> and <Y> denote the switch port and disk slot
+# numbers, respectively, and are typically obtained from sysfs.
+
+AWK=${AWK:-/usr/bin/awk}