manpage: add prompt in --zero-superblock against clustered raid

Clustered raid would be damaged if calls --zero-superblock
incorrectly, so add prompt in --zero-superblock chapter of
manpage. Such as: cluster node1 has assembled cluster-md,
but calls --zero-superblock in other cluster node.

Signed-off-by: Zhilong Liu <zlliu@suse.com>
Signed-off-by: Jes Sorensen <jsorensen@fb.com>

diff --git a/mdadm.8.in b/mdadm.8.in
index f0fd1fce7cbd587438ac91ed3e6d1367f239b62e..e6befeb03c1b37f5602de48de90b76b187a4728b 100644 (file)
--- a/mdadm.8.in
+++ b/mdadm.8.in
@@ -1691,6 +1691,10 @@ overwritten with zeros.  With
 the block where the superblock would be is overwritten even if it
 doesn't appear to be valid.
 
 the block where the superblock would be is overwritten even if it
 doesn't appear to be valid.
 

+.B Note:
+Be careful to call \-\-zero\-superblock with clustered raid, make sure
+array isn't used or assembled in other cluster node before execute it.
+

 .TP
 .B \-\-kill\-subarray=
 If the device is a container and the argument to \-\-kill\-subarray
 .TP
 .B \-\-kill\-subarray=
 If the device is a container and the argument to \-\-kill\-subarray