45Drives.org

autotier: 45Drives’ own contribution back to open source

Every other page in this section covers open-source projects 45Drives builds on — Ceph, ZFS, Samba, NFS, Cockpit. autotier is different: it’s a project 45Drives wrote and open-sourced themselves, released under the GPL for anyone to use, audit, or contribute to — not just customers.

What it actually does

autotier is a FUSE (Filesystem in Userspace) passthrough filesystem that automatically moves files between storage tiers based on how often and how recently they’re accessed. Point it at a fast tier (SSD/NVMe) and a slower, cheaper tier (spinning HDD), and it presents a single unified mount point — hot files migrate to the fast tier automatically, cold files sink to the cheap tier, without anyone manually deciding where anything lives.

Why that’s worth building yourself instead of buying

Storage tiering is normally a feature enterprise storage vendors charge a premium for, bundled into proprietary arrays as a differentiator. 45Drives’ approach was to solve the same problem as an independent, standalone, open-source tool — usable with any Linux storage setup, not gated behind a specific 45Drives hardware purchase, and inspectable by anyone who wants to verify exactly how the tiering decisions get made.

Why this matters beyond the tool itself

This is the clearest evidence on this site that 45Drives’ open-source commitment isn’t just “we chose free software to cut costs” — it’s a two-way relationship. They consume Ceph, ZFS, Samba, Cockpit, and Proxmox from their respective communities, and they give back tools of their own under the same open terms — 45Flow is the other clear example. That’s a meaningfully different posture than a vendor who only uses open source internally while keeping their own value-add proprietary.

autotier moves whole files between tiers based on access patterns. A different technique — block-level caching, where a fast tier transparently accelerates a slower one without moving files wholesale — is handled by Open CAS, which 45Drives also tracks via an Ansible deployment role (Open CAS itself is an Intel-originated project, not a 45Drives creation).

Learn more

See Ceph and ZFS for the storage foundations autotier typically sits on top of, or 45Flow for 45Drives’ other original open-source project.