1 files changed, 3 insertions, 0 deletions

diff --git a/Documentation/md.txt b/Documentation/md.txt
index df0b45515775..4cf5972821a9 100644
--- a/Documentation/md.txt
+++ b/Documentation/md.txt
@@ -302,6 +302,9 @@ Each directory contains:
                          This includes spares that are in the process
                          of being recoverred to
         This list make grow in future.
+        This can be written to.
+        Writing "faulty"  simulates a failure on the device.
+        Writing "remove" removes the device from the array.
 
       errors
         An approximate count of read errors that have been detected on