[PATCH] mdadm.8: Disk coercion with IMSM metadata.

["maciej.naruszewicz" <maciej.naruszewicz@intel.com>]

From: maciej.naruszewicz <maciej.naruszewicz@intel.com>

Actual sizes of disks from different producers may vary,
even though they are claimed to have the same amount of
space. Since creating arrays using IMSM metadata doesn't
support resizing arrays yet, there might be problems when
replacing a disk with a slightly smaller one.

For the time being, disk coercion will not be implemented
for IMSM, however it would be a good idea to inform the
user how to deal with it. Our suggestion is to mention it
in the manual page under the -z option and advise the user
to create arrays using a little less space than the disks
have.

Additionally, the part 'This value can not be used
with CONTAINER metadata such as DDF and IMSM.' was not
clear and was replaced.

Signed-off-by: maciej.naruszewicz <maciej.naruszewicz@intel.com>
---
 mdadm.8.in |   13 ++++++++++---
 1 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/mdadm.8.in b/mdadm.8.in
index 7e8981e..2690e2d 100644
--- a/mdadm.8.in
+++ b/mdadm.8.in
@@ -440,9 +440,16 @@ problems the array can be made bigger again with no loss with another
 .B "\-\-grow \-\-size="
 command.
 
-This value can not be used with
-.B CONTAINER
-metadata such as DDF and IMSM.
+Actual sizes of disks from different manufacturers may slightly differ, even if
+they are said to have the same amount of space. Changing array's size with the 
+.B "\-\-grow \-\-size="
+command is not supported yet by external metadatas such as DDF and IMSM. Creating RAID
+arrays with the
+.B \-z
+option is advised so that the array's size is a bit smaller than the actual maximum
+available data disk's size. Otherwise, replacing a disk in an array with the 'same'
+disk from a different manufacturer is not guaranteed to be always possible due to
+difference in device sizes. 
 
 .TP
 .BR \-Z ", " \-\-array\-size=

---------------------------------------------------------------------
Intel Technology Poland sp. z o.o.
z siedziba w Gdansku
ul. Slowackiego 173
80-298 Gdansk

Sad Rejonowy Gdansk Polnoc w Gdansku, 
VII Wydzial Gospodarczy Krajowego Rejestru Sadowego, 
numer KRS 101882

NIP 957-07-52-316
Kapital zakladowy 200.000 zl

This e-mail and any attachments may contain confidential material for
the sole use of the intended recipient(s). Any review or distribution
by others is strictly prohibited. If you are not the intended
recipient, please contact the sender and delete all copies.