AethelFS (pronounced “Ethel-F-S”) is a user-space filesystem designed for Compute Express Link (CXL) memory and other memory-like devices. It aims to provide a simple, high-performance solution for low-latency storage needs, with an interface modeled after familiar tools like ZFS.

AethelFS’s goal is to make it easy for Linux administrators and developers to experiment with and deploy persistent or volatile memory-backed filesystems—without needing special kernel modules or privileged hardware. The entire system runs in userspace via FUSE, so development and testing can happen on any Linux machine using file-backed devices.

• Linux System Administrators managing high-performance storage for databases, caches, or scientific computing.
• Developers seeking direct, low-latency access to new memory tiers for testing or development—even without physical CXL hardware.

• Simplicity: Avoid complexity—no RAID or advanced volume management.
• Familiarity: Command-line tools (apool, afs) modeled after ZFS for a gentle learning curve.
• Userspace First: Implemented entirely in userspace (FUSE).
• Testability: File-backed device simulation is a priority.

AethelFS consists of:

• Management Utilities:
  • apool: Create, list, and destroy storage pools (backed by files or devices).
  • afs: Create, mount, unmount, list, and destroy filesystems within those pools.
• FUSE Daemon (aethelfsd):
  Handles all file operations, metadata management, and space allocation in userspace.

1. Create a pool:
   sudo apool create -s 1G testpool /tmp/aethelfs.img
2. Create a filesystem:
   sudo afs create testpool
3. Create a mount point:
   mkdir /mnt/test
4. Mount the filesystem:
   sudo afs mount testpool /mnt/test
5. Use it as a regular filesystem!

• No CXL hardware required—use file-backed pools.
• Focus on the apool and afs tools for core management tasks.
• The MVP (minimum viable product) implements basic creation, mounting, file operations, and teardown.