Hi Michael,
if you have a look on the mailing you'll find an answer.....
but anyway..
> /dev/sda1 16368 /boot
> /dev/sda2 8809472 /
> /dev/sda3 65536 <swap>
>
> /dev/sdb1 16368 /boot
> /dev/sdb2 8809472 /
> /dev/sdb3 65536 <swap>
>
> Combine /dev/sda1 and /dev/sdb1 into /dev/md0 and combine /dev/sda2 with
>/dev/sdb2 into /dev/md1. LILO would have root=/dev/md1 for both kernel
images
>on the /boot partition.
>
> Will the new "AUTORAID" configurations handle this situation for a
booting
>kernel? I LOATHE the idea of using initrd.
Lilo just doesn't manage that situation (can't boot from /dev/mdx )
....you need to have the /boot0 and /boot1 (with same content !) and setup
lilo.conf to take care of the dual boot
Again ... looking back on the mailing list you'll find...
But for your plasure:
-----------------------------------------------
Hi Jack,
At 17:59 04.01.99 -0000, you wrote:
>I can sympathise. I decided to postpone trying to RAID the root partition
>until later - much later. At least until I fully understand Linux Software
>RAID. The Software RAID Howto is less of a HOWTO than a FAQ for experienced
>RAIDers... Took me about 20 minutes to figure out that mdadd and raidadd are
>actually the same thing. :)
Been there, done that :-)
1) The docs are way out of sync with reality, there was a mayor overhaul of
the raid code which is available on ftp://ftp.kernel.org/pub/daemons/raid
(or on one of the mirrors). Look for raidtools 0.90 at
alpha/raidtools-19981214-0.90.tar.gz and the coresponding kernel stuff at
alpha/raid-0145*
2) The new code has much better support for root on raid devices -
activation & shutdown of raid devices is included in the kernel. You will
still need a small non-raid partion or disk for storing the kernel and
other stuff needed by lilo at boottime. Also the new raidtools use a config
file /etc/raidtab which really helps in making things easier to manage.
Here's a short account on how I got my raid stuff configured. Partitioning
of disks was done previously, here's what my partition table(s) look like:
Device Boot Begin Start End Blocks Id System
/dev/sda1 1 1 1 8001 83 Linux native
/dev/sda2 * 2 2 197 1574370 fd Unknown
/dev/sda3 198 198 1095 7213185 fd Unknown
/dev/sda4 1024 1096 1111 128520 82 Linux swap
Device Boot Begin Start End Blocks Id System
/dev/sdb1 1 1 1 8001 83 Linux native
/dev/sdb2 * 2 2 197 1574370 fd Unknown
/dev/sdb3 198 198 1095 7213185 fd Unknown
/dev/sdb4 1024 1096 1111 128520 82 Linux swap
/dec/sda1 and /dev/sdab1 are mounted on /boot0 and /boot11 and hold just
the stuff needed by lilo to load the kernel.
For me installation was fairly easy since I've already got serveral systems
running linux; I just built raid tools & a raid kernel on one of the old
systems and copied tools+kernel onto the setup disk; this way you can set
up your raid devices while running off a floppy and install right onto the
/dev/md* device.
* apply the raid0145-19981215-2.0.36 patch to a kernel 2.0.36 to include
the new raid stuff.
* Configure the kernel, say yes to "autodetect RAID partition" and to the
RAID modes you want to use. build & install the kernel.
* compile and install the raid tools v0.90 (./configure; make; make install)
* prepare a configuration file for the raid devices, this goes in
/etc/raidtab by default. Here's what mine looks like:
-----------------------------------------------------------------------------
# /etc/raidtab raid config file
#
raiddev /dev/md0
raid-level 1
nr-raid-disks 2
nr-spare-disks 0
chunk-size 64
device /dev/sda2
raid-disk 0
device /dev/sdb2
raid-disk 1
#
raiddev /dev/md1
raid-level 1
nr-raid-disks 2
nr-spare-disks 0
chunk-size 64
device /dev/sda3
raid-disk 0
device /dev/sdb3
raid-disk 1
-----------------------------------------------------------------------------
This configures two raid-1 mirrors, with two disks each.
* Now, initialize your raid devices:
mkraid /dev/md0
mkraid /dev/md1
Your raid devices are online and useable now, hovever it'll take a while
for initialisatzion of mirrors to finish (in background). you can check the
status of your raid devices by doing cat /proc/mdstat
* put a filesystem on your devices
mke2fs /dev/md0
mke2fs /dev/md1
* enable automatic initialisatzion of raid devices by kernel. Use fdisk to
change the type of the partitions which are part of raid devices to FD:
fdisk /dev/sda
Command (m for help): t
Partition number (1-4): 2
Hex code (type L to list codes): fd
You'll neither have to use raidstart on startup, nor raidstop on shutdown
with this configuration, both are performed automagically by the kernel.
If you don't want to have your devices automatically initialized, you can
of course leave the partition type alone and use raidstart /raidstop to
initialize & shutdown the devices from system startup scripts.
That's it for setup of kernel & partitions.
What took me quite some time was finding a reasonable configuration for
lilo; the aim is to have BOTH sda and sdb bootable so the system still
starts in case one of the disks fails, and to be able to select a kernel
image from either disk on bootup in case just a kernel image somehow gets
damaged. I ended up with two lilo config files, one for each disk, stored
as /etc/lilo.conf.sda and /etc/lilo.conf.sdb.
-----------------------------------------------------------------------------
# LILO configuration file /etc/lilo.conf.sda
#
# Start LILO global section
boot = /dev/sda
disk = /dev/sda
map = /boot0/boot/map
install = /boot0/boot/boot.b
backup = /boot0/boot/boot.0800
message = /boot0/boot/boot_message.txt
prompt
timeout = 50
vga = normal
password = xxxxxxxxxx
restricted
# End LILO global section
# Linux bootable partition config begins
# Images in Disk 0
image = /boot0/vmlinuz
root = /dev/md0
label = Linux_Disk0
read-only
image = /boot0/vmlinuz.001
root = /dev/md0
label = Linux_Disk0_old
read-only
# Images in Disk 1
image = /boot1/vmlinuz
root = /dev/md0
label = Linux_Disk1
read-only
image = /boot1/vmlinuz.001
root = /dev/md0
label = Linux_Disk1_old
read-only
# Linux bootable partition config ends
-----------------------------------------------------------------------------
In the file for the 2nd disk, notice the disk = /dev/sdb bios=0x80 line.
this thells lilo that on bootup, this is acutually going to be the first
disk, even though it's currently the second disk.
-----------------------------------------------------------------------------
# LILO configuration file /etc/lilo.conf.sdb
#
# Start LILO global section
boot = /dev/sdb
disk = /dev/sdb bios=0x80
map = /boot1/boot/map
install = /boot1/boot/boot.b
backup = /boot1/boot/boot.0800
message = /boot1/boot/boot_message.txt
prompt
timeout = 50
vga = normal
password = xxxxxxxxxx
restricted
# End LILO global section
# Linux bootable partition config begins
# Images in Disk 1
image = /kernel1/vmlinuz
root = /dev/md0
label = Linux_Disk1
read-only
image = /kernel1/vmlinuz.001
root = /dev/md0
label = Linux_Disk1_old
read-only
# Images in Disk 0
image = /kernel0/vmlinuz
root = /dev/md0
label = Linux_Disk0
read-only
image = /kernel0/vmlinuz.001
root = /dev/md0
label = Linux_Disk0_old
read-only
# Linux bootable partition config ends
-----------------------------------------------------------------------------
Now some hints on maintenance of your raid devices: The raid devices are
automatically checked by the kernel; in case of problems (power down
without proper shutdown for example) the devices are automatically
resynchronized, again see /proc/mdstat for current status.
If one of your disks actually fails and has to be replaced you can use the
raidhotremove and raidhotadd programs (actually just symlinks to
/sbin/raidstart, automatically created on installation of raidtools) to
remove defect drives and/or to add new devices. say your disk /dev/sdb
died and had to be replaced; your system is now running solely off
/dev/sda, /proc/mdstat shows that only the first disk in the mirror(s) is
active.
raidhotremove /dev/md0 /dev/sdb2
raidhotremove /dev/md1 /dev/sdb3
Now you've got mirrors consisting of just one disk each, but at least
they're healty again.
raidhotadd /dev/md0 /dev/sdb2
raidhotadd /dev/md1 /dev/sdb3
Will add the new disk to the mirror(s) and initialize the new disk so you
end up with a consistant mirror again. Syschronisation runs in the
background, again see /proc/mdstat for current status.
Hope this helps,
Martin
--------------------------------------------------
Martin Bene vox: +43-664-3251047
simon media fax: +43-316-813824-6
Andreas-Hofer-Platz 9 e-mail: [EMAIL PROTECTED]
8010 Graz, Austria
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