http://www.debian.org/releases/stable/i386/release-notes/ch-upgrading.en.html
backup /etc, /var/lib/dpkg and the output of dpkg --get-selections "*"
change /etc/apt/preferences
New /etc/apt/sources.list:
------------------
deb http://security.debian.org/ etch/updates main contrib non-free
deb ftp://ftp.nl.debian.org/debian etch main contrib non-free
deb-src ftp://ftp.nl.debian.org/debian etch main contrib non-free
------------------
aptitude -y -s -f --with-recommends dist-upgrade
shows how much free space you need
aptitude upgrade
does a minimal upgrade without removing the packages
aptitude install initrd-tools
aptitude install udev
aptitude install discover
make sure lvm2 is installed, as lvm 1 is incompatible, as are snapshot volumes, so they need to be removed from /etc/fstab and can safely be destroyed.
Also make sure dmsetup is installed.
If the machine exports NFS volumes, make sure the portmapper is listening to all ports (/etc/default/portmap)
Make sure the packages which were changed are running under the new configuration
Upgrade the Kernel:
apt-cache search linux-image-2.6- | grep -v transition
aptitude install linux-image-2.6-686
/etc/lilo.conf initrd configuration. use mkinitrd to create it if it isn't there allready. Check the existence of the files!
-----------------
image=/vmlinuz
label=Linux
read-only
initrd=/initrd.img
# restricted
# alias=1
image=/vmlinuz.old
label=LinuxOLD
read-only
optional
# restricted
# alias=2
-------------------
rerun lilo after editing lilo.conf
check mountpoints and exports - make sure nothing is accessing them before the next step, so make sure any servers using those mountpoints have unmounted them cleanly!
reboot
pray a bit
login
backup the mysql databases
aptitude dist-upgrade (nb make sure of free diskspace!)
aptitude update gets the package signature checking mechanism
in /etc/default/snmpd
change
SNMPDOPTS='-Lsd -Lf /dev/null -u snmp -I -smux -p /var/run/snmpd.pid'
to allow access from all hosts
/etc/X11/xdm/Xaccess there's some broadcast option set which I'm not sure yet if it's important.
make sure that in /etc/kernel-img.conf
do_bootloader = Yes
exists
check the raid arrays
mdadm --detail /dev/md0
(http://svn.debian.org/wsvn/pkg-mdadm/mdadm/trunk/debian/README.upgrading-2.5.3?op=file)