Multiple devices driver for Linux
  Harald Hoyer <HarryH@Royal.Net>
  26.10.98

  This driver lets you combine several hard disk partitions into one
  logical block device. This can be used to combine several redundant
  hard disks to a  RAID1/4/5 device so as to provide protection against
  hard disk failures.
  ______________________________________________________________________

  Table of Contents


  1. Authors

  2. Tools and Documentation Sources

  3. Boot Support

     3.1 Introduction
     3.2 Boot Arguments
     3.3 Usage with boot loader
        3.3.1 lilo
        3.3.2 loadlin


  ______________________________________________________________________

  1.  Authors


  o  Copyright (C) 1994-96 Marc ZYNGIER

  o  kerneld support by Boris Tobotras <boris@xtalk.msk.su>

  o  Boot support for linear and striped mode by Harald Hoyer

  o  RAID-1/RAID-5 extensions by: Ingo Molnar, Miguel de Icaza, Gadi
     Oxman


  o  Changes for kmod by: Cyrus Durgin

  o  Author of this document: Harald Hoyer

  2.  Tools and Documentation Sources


  More information and the necessary tools are available over FTP (user:
  anonymous) from <ftp://sweet-smoke.ufr-info-p7.ibp.fr/pub/Linux> in
  the md package and the md-FAQ.

  Please read drivers/block/README.md and the relevant section of the
  Disk-HOWTO, available via FTP (user: anonymous) from
  <ftp://sunsite.unc.edu/pub/Linux/docs/HOWTO>.

  Marc ZYNGIER <zyngier@ufr-info-p7.ibp.fr> or <maz@gloups.fdn.fr>


  3.  Boot Support


  3.1.  Introduction
  I added boot support for the md device, because if you wanted to have
  a md based root device, you had to deal with ramdisks and that was
  very uncomfortable.  So now you have direct boot and speed support.

  Harald Hoyer

  3.2.  Boot Arguments


  You can boot (if you selected boot support in the configuration) with
  your md device with the following kernel command line:

  md=<md no.>,<level>,<chunk size>,<fault level>,dev0,dev1,...,devn


     md no.
        is the number of the md device ...

     0  means md0,

     1  md1,

     2  md2,

     3  md3

     raid level
        is one of the following numbers

     -1 means linear mode

     0  striped mode (raid-0)

     5  raid-5 mode

  other modes are currently not able to boot without the md tools.

     chunk size
        is for raid-0 and raid-1 only. Set the chunk size as PAGE_SIZE
        << n.

     fault level
        is for raid-1 only. Set the maximum fault number as n. Currently
        unsupported due to lack of boot support for raid1.

     dev0-devn
        are e.g. /dev/hda1,/dev/hdc1,/dev/sda1,/dev/sdb1

     example loadlin:
        e:\ loadlin\loadlin e:\zimage root=/dev/md0
        md=0,0,4,0,/dev/hdb2,/dev/hdc3 ro

  3.3.  Usage with boot loader


  3.3.1.  lilo


     WARNING:
        If you want to use a md root partition, you have to place your
        kernel image zImage, bzImage or vmlinuz on a non-raid partition,
        e.g.  a small /boot ext2 partition located in the first 512MB of
        the harddisk. lilo can't read from a md device at boot time, so
        be careful.


  You have to add s.th. like this to your lilo.conf:

  append="md=0,0,3,0,/dev/hda3,/dev/hdc2"

  3.3.2.  loadlin


  Using loadlin causes no problem with a md root partition, cause
  loadlin must already have access to the image.