mdadm.man: added encouragement to shrink filesystem before array.

Suggesting by Rory Jaffe <rsjaffe@gmail.com> to make the danger
of shrinking, and to recommended avoidance technique, more explicit.

Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/mdadm.8.in b/mdadm.8.in
index 08e425584725997b337455f43b5a14309c24b46f..05ae34f66177010707a6ea98e8f0f76c0b311d8a 100644 (file)
--- a/mdadm.8.in
+++ b/mdadm.8.in
@@ -2158,8 +2158,12 @@ space to start being used.  If the size is increased in this way, a
 are synchronised.
 
 Note that when an array changes size, any filesystem that may be
 are synchronised.
 
 Note that when an array changes size, any filesystem that may be

-stored in the array will not automatically grow to use the space.  The
-filesystem will need to be explicitly told to use the extra space.
+stored in the array will not automatically grow for shrink to use or
+vacate the space.  The 
+filesystem will need to be explicitly told to use the extra space
+after growing, or to reduce its size
+.B prior
+to shrinking the array.

 
 Also the size of an array cannot be changed while it has an active
 bitmap.  If an array has a bitmap, it must be removed before the size
 
 Also the size of an array cannot be changed while it has an active
 bitmap.  If an array has a bitmap, it must be removed before the size


@@ -2189,7 +2193,8 @@ increase or decrease the number of devices in a RAID5 or RAID6.
 
 When decreasing the number of devices, the size of the array will also
 decrease.  If there was data in the array, it could get destroyed and
 
 When decreasing the number of devices, the size of the array will also
 decrease.  If there was data in the array, it could get destroyed and

-this is not reversible.  To help prevent accidents,
+this is not reversible, so you should firstly shrink the filesystem on
+the array to fit within the new size.  To help prevent accidents,

 .I mdadm
 requires that the size of the array be decreased first with
 .BR "mdadm --grow --array-size" .
 .I mdadm
 requires that the size of the array be decreased first with
 .BR "mdadm --grow --array-size" .