Forgive me for the ignorance of my question.
I'm tired creating backups, or loosing data. Let's be honest, sometimes it happens. Does a filesystem that never deletes/overwrites anything exist?
I envision something like an append only filesystem where you all files in your hard drive are under some OS level 'version control' and you can rollback to any version you want. Only files in my home dir would be enough. Obviously once space runs out it would start overwriting the oldest versions.
The affordable version of what you are describing is a set of NAS class servers that use something like DRBD or Ceph for multi-node replication and rsnapshot for local snapshots/versioning if LVM. If using LVM, then rsnapshot should be configured to save its snapshot where the remote clients can not write to it.
Look into setting up Ceph clusters if you plan to build something that will need to scale really large on individual volumes across multiple nodes. Ceph supports creating snapshots. There are pros and cons to solutions such as DRBD, LVM and Ceph. That would be a topic in and of itself. Others here are mentioning ZFS and that is also a popular solution but I have never used it and can't comment on it.
In summary if I was asked to build something that would grow to unknown size, require snapshots to roll-back files to a specific date and be fault tolerant I would go with Ceph. As a bonus feature there are libraries and tools to present Ceph volumes as S3-like buckets. There are ansible playbooks for setting up Ceph clusters. Ceph has some really good security features as well.