Merge branches 'for-4.11/upstream-fixes', 'for-4.12/accutouch', 'for-4.12/cp2112...

[mirror_ubuntu-artful-kernel.git] / Documentation / device-mapper / dm-raid.txt

diff --git a/Documentation/device-mapper/dm-raid.txt b/Documentation/device-mapper/dm-raid.txt
index c84cdd220f9d975b1df41478af335a6497207cca..0d199353e4776b60e40062cd3f57f98be6166cb7 100644 (file)
--- a/Documentation/device-mapper/dm-raid.txt
+++ b/Documentation/device-mapper/dm-raid.txt
@@ -161,6 +161,15 @@ The target is named "raid" and it accepts the following parameters:
                the RAID type (i.e. the allocation algorithm) as well, e.g.
                changing from raid5_ls to raid5_n.
 
+       [journal_dev <dev>]
+               This option adds a journal device to raid4/5/6 raid sets and
+               uses it to close the 'write hole' caused by the non-atomic updates
+               to the component devices which can cause data loss during recovery.
+               The journal device is used as writethrough thus causing writes to
+               be throttled versus non-journaled raid4/5/6 sets.
+               Takeover/reshape is not possible with a raid4/5/6 journal device;
+               it has to be deconfigured before requesting these.
+
 <#raid_devs>: The number of devices composing the array.
        Each device consists of two entries.  The first is the device
        containing the metadata (if any); the second is the one containing the
@@ -245,6 +254,9 @@ recovery.  Here is a fuller description of the individual fields:
        <data_offset>   The current data offset to the start of the user data on
                        each component device of a raid set (see the respective
                        raid parameter to support out-of-place reshaping).
+       <journal_char>  'A' - active raid4/5/6 journal device.
+                       'D' - dead journal device.
+                       '-' - no journal device.
 
 
 Message Interface
@@ -318,3 +330,4 @@ Version History
        fails reading a superblock. Correctly emit 'maj:min1 maj:min2' and
        'D' on the status line.  If '- -' is passed into the constructor, emit
        '- -' on the table line and '-' as the status line health character.
+1.10.0  Add support for raid4/5/6 journal device