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Migrating from any Linux Distros to *Debian*
Why Debian???
Simple to maintain. Tell me about all the wasted time I had
installing and upgrading non-debian based Linux machines.
Very versatile programs, Debootstrap, Alien, Apt & Dpkg!
Debian has a really nice tool called Debootstrap. It can
strap(convert) theoretically(IMHO), any 'chroot' obeying OS to
Debian. So armed with this knowledge, Its possible to first install a
'chroot' obeying OS on a machine and then convert to Debian.
So a rough method would be
Install a working Linux Distro
Debootstrap Debian on it
For example I used a blade server IBM JS20 for the experiment.
Known OS as of (Aug-1-05) these are some major Linux distros
supporting JS20, namely SUSE SLES 9.0, Redhat RHEL 9.0, Fedora Core 4
, Yellow Dog Linux and many more.See here for a detailed list.
Steps
So we will start out with SUS SLES 9.0. Be sure to download
the PowerPC edition, else you might have to rip out your blades and
install some x86 based PresHots there. Anyways once that is done
burn them on the CD's. I think only the first 4 CD's required. For a x86 machine download the appropriate CD-ISO and burn it.
For PowerPC based JS-20 blades
Note: If you have a single Harddisk
make
/dev/hda1 Primary PPC PReP Boot
0.5MB
/dev/hda2 Primary Linux Swap
(depending upon server memory some GB's)
/dev/hda3 Primary Linux Ext3 (/debian
some size, make atleast 5GB, Harddisk space is cheap Dude)
/dev/hda5 Primary Linux Ext3 (/home
partition)
/dev/hda6 Primary Linux Ext3 (/ for
Suse)
And if you have an additional hard
disk, Do whatever you want with it.
For Intel x86 machine: Just make sure you have an extra partition somewhere of the size about 5GB+ and mount as /debian
Do a minimal Install and reboot. When you reboot, due to the
installation the blade will try to boot from the Hard disk and
fail on the blade server!!!. This would not happen in case of a x86 machine, in which grub/lilo would load normally.
The Reason?
JS-20 Specific stuff Yaboot is slightly stupid, It
will(IMHO) try to load the first Linux Primary partition and fail as
it is /debian in our case). To get around this, change the boot
sequence through the management module and boot from the CD and when
the boot prompt of the CD shows use the following command to use the
CD's Kernel to mount and boot /dev/hda6 AKA / of SUSE. Note: This problem won't occur on x86 based machines.
Both JS-20 and Intel x86
When you are on the command prompt, again fire up YAST2. And
through YAST2 options install the following program( You might have
to search for the software in YAST2 first). The Software needed are
wget and perl. I suppose a minimal version does install perl but not
not wget. Once wget is installed we can install 'debootstrap'
program.
Now debootstrap is available only as a .deb package. And SUSE
default packages are in .rpm format. We need to convert .deb to
.rpm. So we will use 'alien'. You can get 'alien' here
alien.
Either Download it using wget or burn it to a cd. Dont burn it right
now, But wait till I tell.
Once alien is acquired(not through roswell), Get debootstrap
debootstrap
and either burn it or use wget through your blade, if you have a
network connection through the blades. Once this is done use the cd,
and copy both the programs to your blade. Alien in the gzip format
so Unzip it and as you should do for any software, read the README
and follow instructions.
Once the above stage is finished, use Alien to convert .deb
to .rpm via 'alien -r debootstrap_XXX_XXX.deb' XXX=version might
be different for everyone.
You will then get a rpm package for debootstrap which you can
install via 'rpm -ivh debootstrap_XXX.rpm' In case you get some
error like some .so not found, search on the net which library is
that .so(b) a part and install it via YAST2 as we did earlier for
perl and wget.
On installation debootstrap will be installed(in
/usr/sbin/debootstrap). Now you are ready to bootstrap debian. As
you remembered we allocated a partition /dev/hda3 and mounted it as
/debian. At this point we have 2 options, first debootstrap via the
net or via a special file called
basedebs.tar(basedebs.tar for x86 and
basedebs.tar for JS-20)
Using local basedebs.tar
debootstrap --arch powerpc
--unpack-tarball /path-to-downloaded/basedebs.tar woody /debian
--arch = powerpc in our case
/debian = place where we want to
install our stuff
Using Internet
debootstrap --arch powerpc woody
/debian
woody, or sarge or sid etc the name
depends on the scripts found here for debootstrap
/usr/lib/debootstrap/scripts/, So in your case you might want to
substitute the required script.
After some time and an occasional coffee, the /debian would
have wonderfully converted to a full fledged Linux directory
structure and ready to be customized. At this point chroot will come
into play. In a nutshell, chroot will 'pseudo mount' the given
directory as / and run whatever sh you want on that /. e.g. say you
are in /blah/blah2 and use 'chroot . /bin/bash' in it. It will
pseudo mount /blah/blah2 as / and run bash.
We will do the same for /debian and run 'chroot . /bin/bash'
. Now we are in debian mode!!!!wowey !!!. Now we will run our
favourite debian command (for me it is favourite) base-config and
start all configuration. Choose whatever we install and let debian
install all the packages(X & others). As you can see we needn't
need a network connection at all. But you surely should have network
connection at this point, as other than the freaking hvc0 terminal
we don't have anyway to connect to the blade(remember no video
cards)
Hmmm.. i always forget to mention this, somethings would fail
if you do an immediate base-config after chroot'ing'. You might want
to mount proc. Proc allows some really system specific stuff stored
in memory(like the name of our powerpc architecture) so that
base-config doesn't get confused.
mount -t proc proc /proc
Now you can modify /etc/fstab to
show the current harddisk status. You can copy your old fstab from
SUSE installation to your new Debian installation. Make sure that
you do it out of your chroot environment. ;-)
You might at this point want to
install some very essential tools like nano, module-init-utils,
ssh and mc. Use apt-get to do that.
apt-get install nano mc
module-init-utils ssh
and make sure it
has this lines
auto lo
iface lo inet
loopback
auto eth0
iface eth0 inet dhcp
This makes sure than lo and eth0
are loaded at runtime so that we can remotely connect to our blades.
You might want to add eth1 if you have more network ports. You might
also want to set static ip in some circumstances, In that case refer
to the syntax of interfaces file.
We wont install a custom
kernel-image as to this date i am not able to get a debian
kernel-image working on JS20. So we will make SUSE kernel boot our
OS. For that exit the chroot environment using plain 'exit'
now copy the whole /boot to
/debian/boot (all files and subdirectories).
For JS-20: Copy /etc/yaboot.conf
to /debian/etc/yaboot.conf
For x86:
For JS-20:Initially we know that yaboot did
not boot on because of the non-presence of the yaboot.conf and
kernel on the first Linux partition. Now as we had bootstrapped the
whole system to the first Linux partition, and copied the kernel
(boot files) to the /debian we can now boot the system using the
SUSE kernel+Debian system. But before that we will have to modify
the /debian/yaboot.conf and make sure that yaboot.conf has the
/dev/hda6 line changed to /dev/hda3 line that is the kernel and /
are on /dev/hda3 and not on /dev/hda6. eg.yaboot.conf file.
For x86:To write something about lilo and grub
For JS-20:Also copy the
/lib/modules/2.6.5-7.97-pseries64 to the /debian/lib/modules/
2.6.5-7.97-pseries64. Add the bcm5700 line in the /etc/modules line.
For x86:Also copy the
/lib/modules/2.6.XXX to the /debian/lib/modules/
2.6.XXX. Add the bcm5700(netwrok card module name) line in the /etc/modules line.
hvc0:1235:respawn:/sbin/getty
-L 9600 hvc0 vt100
This concludes the whole tutorial on how-to migrate JS-20 from SUSE 9.0 to Debian. Report to me at abhishek(at)ieee.org (substitute (at) with @) if you find any errors.
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