Upgrade to Wheezy

Steps to be performed to upgrade from Squeeze (amd64) to Wheezy. I don't explain why a certain step is done - read the manual found at step one. You should know what you're doing!

preperations

read http://www.debian.org/releases/wheezy/amd64/release-notes/index.en.html
backup your data
backup as recommended:

tar czf ~/squeeze-bkup.tgz /etc /var/lib/dpkg /var/lib/apt/extended_states \
/var/lib/aptitude/pkgstates
 
dpkg --get-selections "*" > ~/dpkg-selections.squeeze

prepare for recovery
remove conflicting packages
review actions pending in package manager: To perform this review, launch aptitude in “visual mode” and press g (“Go”). If it shows any actions, you should review them and either fix them or implement the suggested actions. If no actions are suggested you will be presented with a message saying “No packages are scheduled to be installed, removed, or upgraded”.

# Checking packages status
 
dpkg --audit
dpkg -l | pager
aptitude search "~ahold" 
dpkg --get-selections | grep hold

update the package list
recorde the session

script -t 2>~/upgrade-wheezystep.time -a ~/upgrade-wheezy1.script

let's go:

apt-get update

make sure you have sufficient space for the upgrade
kernel flavour selection only applicable if you're running an i386 sytem
minimal system upgrade:

apt-get upgrade

upgrade the system:

apt-get dist-upgrade

Possible issues during upgrade

transitioning from ia32-libs to multiarch (the ia32-libs package is now a transitional package)
in order to allow installation of i386 packages on an amd64 system, execute the following commands:

dpkg --add-architecture i386
apt-get update
apt-get install ia32-libs

upgrade the kernel

# determine your kernel metapackage:
dpkg -l "linux-image*" | grep ^ii
 
# install kernel, e.g.
apt-get install linux-image-2.6-686
 
# if you get an error message saying "W: Possible missing firmware ..." 
# you will need the nonfree firmware packages:
apt-get install firmware-linux-nonfree
 
update-grub

Reboot and we're done.

Debian