There are two core backup mechanisms active.
The first is an instance of backup2l which runs daily. See /etc/cron.daily/zz-backup2l. This creates a generational incremental backup in /archive/backups - that is, on the non-SSD storage. These backups expire after 2 months. Currently they are also rsync'd to Jim's home server, to provide offsite backup.
The second is a daily rsync-backed backup provided by Bytemark. See /etc/cron.daily/zz-byteback. This updates a snapshot of the server state, and so does not retain historical information.