lkml.org 
[lkml]   [2004]   [Nov]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH][resend] md: Documentation/md.txt update
Date
Updates to Documentation/md.txt - included some extra info I found out while
digging deeper into init/do_mounts_md.c

Signed-off-by: James Nelson <James4765@gmail.com>

diff -urN --exclude='*~' linux-2.6.9-original/Documentation/md.txt linux-2.6.9/Documentation/md.txt
--- linux-2.6.9-original/Documentation/md.txt 2004-10-18 17:54:38.000000000 -0400
+++ linux-2.6.9/Documentation/md.txt 2004-11-10 18:33:43.224334682 -0500
@@ -45,7 +45,8 @@
When md is compiled into the kernel (not as module), partitions of
type 0xfd are scanned and automatically assembled into RAID arrays.
This autodetection may be suppressed with the kernel parameter
-"raid=noautodetect".
+"raid=noautodetect". As of kernel 2.6.9, only drives with a type 0
+superblock can be autodetected and run at boot time.

The kernel parameter "raid=partitionable" (or "raid=part") means
that all auto-detected arrays are assembled as partitionable.
@@ -55,13 +56,13 @@
------------------

The md driver can support a variety of different superblock formats.
-(It doesn't yet, but it can)
+Currently, it supports superblock formats "0.90.0" and the "md-1" format
+introduced in the 2.5 development series.

-The kernel does *NOT* autodetect which format superblock is being
-used. It must be told.
+The kernel will autodetect which format superblock is being used.

Superblock format '0' is treated differently to others for legacy
-reasons.
+reasons - it is the original superblock format.


General Rules - apply for all superblock formats
@@ -69,6 +70,7 @@

An array is 'created' by writing appropriate superblocks to all
devices.
+
It is 'assembled' by associating each of these devices with an
particular md virtual device. Once it is completely assembled, it can
be accessed.
@@ -76,10 +78,10 @@
An array should be created by a user-space tool. This will write
superblocks to all devices. It will usually mark the array as
'unclean', or with some devices missing so that the kernel md driver
-can create approrpriate redundancy (copying in raid1, parity
+can create appropriate redundancy (copying in raid1, parity
calculation in raid4/5).

-When an array is assembled, it is first initialised with the
+When an array is assembled, it is first initialized with the
SET_ARRAY_INFO ioctl. This contains, in particular, a major and minor
version number. The major version number selects which superblock
format is to be used. The minor number might be used to tune handling
@@ -101,15 +103,16 @@


Specific Rules that apply to format-0 super block arrays, and
- arrays with no superblock (non-persistant).
+ arrays with no superblock (non-persistent).
-------------------------------------------------------------

An array can be 'created' by describing the array (level, chunksize
etc) in a SET_ARRAY_INFO ioctl. This must has major_version==0 and
raid_disks != 0.
-Then uninitialised devices can be added with ADD_NEW_DISK. The
+
+Then uninitialized devices can be added with ADD_NEW_DISK. The
structure passed to ADD_NEW_DISK must specify the state of the device
and it's role in the array.

-One started with RUN_ARRAY, uninitialised spares can be added with
+Once started with RUN_ARRAY, uninitialized spares can be added with
HOT_ADD_DISK.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
\
 
 \ /
  Last update: 2005-03-22 14:07    [W:0.032 / U:0.392 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site