[1,of,7] DM RAID: documentation updates

Commit Message

Jonthan Brassow June 8, 2011, 10:13 p.m. UTC

Updates to the dm-raid.txt documentation.

Add a little more information for some of the parameters of a dm-raid CTR table
and add a little more clarity to how parameters are printed when 'dmsetup table'
is issued.

Signed-off-by: Jonathan Brassow <[e-mail]>



--
dm-devel mailing list
[e-mail]
https://www.redhat.com/mailman/listinfo/dm-devel

Patch

Index: linux-2.6/Documentation/device-mapper/dm-raid.txt
===================================================================
--- linux-2.6.orig/Documentation/device-mapper/dm-raid.txt
+++ linux-2.6/Documentation/device-mapper/dm-raid.txt
@@ -22,10 +22,15 @@  planned for the future.)  The list of re
 is the same for all the current raid types.  The required parameters are
 positional, while the optional parameters are given as key/value pairs.
 The possible parameters are as follows:
- <chunk_size>           Chunk size in sectors.
+ <chunk_size>           Chunk size in sectors.  This parameter is often called
+ 			"stripe size".  It is the only required parameter and
+			must be the first parameter.
  [[no]sync]             Force/Prevent RAID initialization
  [rebuild <idx>]        Rebuild the drive indicated by the index
- [daemon_sleep <ms>]    Time between bitmap daemon work to clear bits
+ [daemon_sleep <ms>]    Time between bitmap daemon work to clear bits.  A longer
+ 	       		time means less bitmap I/O, but potentially longer resync
+			time after a failure due to a less frequent clearing of
+			the bitmap.
  [min_recovery_rate <kB/sec/disk>]      Throttle RAID initialization
  [max_recovery_rate <kB/sec/disk>]      Throttle RAID initialization
  [max_write_behind <sectors>]           See '-write-behind=' (man mdadm)
@@ -55,9 +60,12 @@  Examples:
         raid4 4 2048 min_recovery_rate 20 sync\
         5 - 8:17 - 8:33 - 8:49 - 8:65 - 8:81
 
-Performing a 'dmsetup table' should display the CTR table used to
-construct the mapping (with possible reordering of optional
-parameters).
+Performing a 'dmsetup table' will display the CTR table used to construct the
+mapping.  The optional parameters will always be printed in the order listed
+above.  "sync" or "nosync" will always be printed before the other arguments,
+for example.  If the user passes in optional arguments in a different order,
+the results of 'dmsetup table' will differ from the CTR table used to construct
+the mapping.
 
 Performing a 'dmsetup status' will yield information on the state and
 health of the array.  The output is as follows: