How to upgrade FreeBSD 8.2 to FreeBSD 9.0 with Virtio

Step 1: The upgrade

Let’s get right to it. Here’s the first step in the upgrade process:

freebsd-update upgrade -r 9.0-RELEASE

Once all files have been fetched, you will be asked a number of questions about merging config-files. They all seemed reasonable to me, so I just answered ‘y’ to all of them, but it might differ for you. Make sure you read the diff before accepting it.

If you get the following error:

The update metadata is correctly signed, but failed an integrity check.
Cowardly refusing to proceed any further.

Then simply patch your freebsd-update using the following command (source):

sed -i '' -e 's/=_/=%@_/' /usr/sbin/freebsd-update

and then re-run the upgrade command again.

If that went fine, it’s time to update the actual system. To do that, run:

freebsd-update install

Onde the update is done, reboot your system:

shutdown -r now

When it comes back up, make sure you run the install-again to install again to intall the userland updates:

freebsd-update install

Once you’ve run this, you’ll get the message:

Completing this upgrade requires removing old shared object files.

Please rebuild all installed 3rd party software (e.g., programs
installed from the ports tree) and then run 
"/usr/sbin/freebsd-update install"  again to 
finish installing updates.

This is of course a massive pain in the butt, but you need to do this nonetheless. Depending on how many packages from ports you have installed, this may take everything from a few minutes to a long time.

The easiest way to do this is to run portupgrade (if you don’t have portupgrade, install it from ‘sysutils/portupgrade’):

rm /var/db/pkg/pkgdb.db && pkgdb -Ffuv && portupgrade -afp

I added the ‘p’-flag, as this allows you to run ‘portupgrade -afP’ on other nodes (assuming you have a shared ports-tree) and just install the packages without having to re-compile them.

Finally, when you’ve done this, you can run (for the last time):

freebsd-update install

Step 2: Installing Virtio

Nowadays, Virtio is available in ports. That’s of course great, as that reduces the burdan of installing it. All you need to do is to run:

cd /usr/ports/emulators/virtio-kmod && make clean install

Once the kernel-module is installed, add the following to /boot/loader.conf:

virtio_load="YES"
virtio_pci_load="YES"
virtio_blk_load="YES"
if_vtnet_load="YES"
virtio_balloon_load="YES"

Next, we need to tell the system to actually use Virtio. The above commands assume that you are using ‘emX’ as your network-interface and /dev/daX or /dev/adX as your harddrive. It also that you’re using /etc/pf.conf as your firewall config, and that you have coded it to use the NIC’s name and not just IP-address. If you’re not using PF or use a different setup, simply skip the last command.

cp /etc/fstab /etc/fstab.bak && cat /etc/fstab.bak | perl -pe "s/ad/vtbd/g; s/da/vtbd/g;" > /etc/fstab
cp /etc/rc.conf /etc/rc.conf.bak && cat /etc/rc.conf.bak | perl -pe "s/em/vtnet/g;" > /etc/rc.conf
cp /etc/pf.conf /etc/pf.conf.bak && cat /etc/pf.conf.bak | perl -pe "s/em/vtnet/g;" > /etc/pf.conf

Now power off the system to make the changes to the host:

shutdown -p now

When the system stops, update all network drivers to Virtio and change the primary disk to block-driver.

You should now be able to boot into the new system with Virtio and enjoy a lot better (and more reliable) speed.

source: http://viktorpetersson.com/2012/01/16/how-to-upgrade-freebsd-8-2-to-freebsd-9-0-with-virtio/