Raspberry Pi as third node

This short wiki will document how to prepare and configure a Rasberry Pi to use as third node (widness) in a Proxmox cluster. This howto has been tested on a Rasberry Pi v3 but should also work on any other Rasberry Pi version where Raspbian is available. Raspbian version is Jessie.

1. Login as root on your Pi
2. Install Debian Jessie (Standard system utilities and SSH server)
3. echo "deb http://ftp.debian.org/debian jessie-backports main contrib" > /etc/apt/sources.list.d/jessie-backports.list
4. gpg --keyserver pgpkeys.mit.edu --recv-key 7638D0442B90D010 && gpg -a --export 7638D0442B90D010 | apt-key add -
5. gpg --keyserver pgpkeys.mit.edu --recv-key 8B48AD6246925553 && gpg -a --export 8B48AD6246925553 | apt-key add -
6. apt-get update
7. apt-get -t jessie-backports install corosync
8. sed -i 's/without-password/yes/' /etc/ssh/sshd_config && systemctl restart ssh
9. scp <ip of pve node>:/etc/corosync/* /etc/corosync
10. add new node under nodelist in /etc/corosync.conf (copy one of the current and adjust)

    for NODE in <ip of pve node 1> <ip of pve node 2>; do
    scp /etc/corosync/corosync.conf $NODE:/etc/corosync
    done

11. ssh <ip of pve node 1> systemctl restart corosync
12. ssh <ip of pve node 2> systemctl restart corosync
13. systemctl start corosync
14. run corosync-quorumtool to check all three nodes are registret as online and that there is quorum:

    corosync-quorumtool | grep Quorate:
    Quorate:          Yes