Dec 102011

Once upon a time, virtual was installed under full virtualization (KVM) -mode. Network wasn’t bridged, it was routed.

And then the problem: IPv6 -traffic flowed nicely inbound, but outbound was capped to about 128 kbps.

Troubleshooting: after googling around with ipv6, kvm and debian we came around to this, Debian bug report about GSO Ipv6 issues under KVM. It’s supposed to be fixed in 2.6.32-5-amd64 (2.6.32-39) -package…well, upgrading didn’t work for us, propably another (similar kind of) bug or something needs to be done at host-machine.

Workaround: ¬†disabling virtio_net’s gso worked for us:

ifdown eth0; modprobe -r virtio_net; modprobe virtio_net gso=0; ifup eth0
Dec 092011

Debian Squeeze was released 06.02.2011 and Lenny’s support will (probably) be is discontinued since 06.02.2012.


Problem: apt-get update && apt-get dist-upgrade broke everything, server did not boot anymore.

Troubleshooting: squeeze has grub2, which our Xen 3.x and pygrub didn’t understand

Solution: upgrading with following steps, use apt-get or aptitude, whichever you like.

  1. Update Lenny
    aptitude update
    aptidude upgrade
  2. Replace lenny with squeeze in /etc/apt/sources.list – or add necessary entries to another file under /etc/apt/sources.list.d/
    deb squeeze main contrib non-free
    deb squeeze-updates main contrib non-free
    deb squeeze/updates main contrib non-free
  3. Update repository
    aptitude update
  4. Upgrade critical parts first
    aptitude install dpkg apt aptitude
  5. (Dist-)upgrade rest
    aptitude upgrade
    aptitude dist-upgrade
  6. Replace grub2 with grub1 (or just keep your old menu.lst at /boot/grub/)
    aptitude purge grub-pc
    aptitude install grub-legacy
  7. Check that /boot/grub/menu.lst exists and defaults to right kernel
  8. Reboot and hope for the best


Also remember to use 2.6.39 -kernel from backports for live migration to work.
Update 01/2013: 2.6.32 -kernel usually works just fine, Lenny’s EOL date is 6.2.2012.