Super imporant step before you start with the upgrade is to check ALL your OpenVZ containers run SUPPORTED distros! Very short and hard to notice list is on Promox’s LXC wiki page.
I had to revert back to version 3.4 as most of the containers we run are based on CentOS7 and various versions of Fedora. So I have only couple of issues that appeared during upgrade and I was able to fix them:
- Broadcom network cards – Few warnings about
bnx2firmware missing appeared during
apt-get dist-upgrade. Check the output and if you get, them install manually
firmware-bnx2manually, otherwise you will end up with no network after reboot to Promox 4.
- Broken network in CentOS containers – Once you convert your CentOS containers from OpenVZ to LXC, you can start the them, but you may experience limited network connectivity. It is caused by missing default gateway as old
venetdevice may be configured to set default gateway in
/etc/sysconfig/network. Change it to the device you created while converting container. You can also delete
/etc/sysconfig/network-scripts/as they are no longer needed.