Clarify when update=super-minor happens automatcially

.. in man page

diff --git a/mdadm.8 b/mdadm.8
index 3ebef842b3934f0e88d99f07b5acee1b50cb1b01..076ee637496dfdb64f6d659817bace00978b7d13 100644 (file)
--- a/mdadm.8
+++ b/mdadm.8
@@ -724,8 +724,15 @@ The
 option will update the
 .B "preferred minor"
 field on each superblock to match the minor number of the array being
 option will update the
 .B "preferred minor"
 field on each superblock to match the minor number of the array being

-assembled.  This is not needed on 2.6 and later kernels as they make
-this adjustment automatically.
+assembled.
+This can be useful if
+.B --examine
+reports a different "Preferred Minor" to
+.BR --detail .
+In some cases this update will be performed automatically
+by the kernel driver. In particular the update happens automatically
+at the first write to an array with redundancy (RAID level 1 or
+greater) on a 2.6 (or later) kernel.

 
 The
 .B uuid
 
 The
 .B uuid