Storage

The Nexus storage stack is designed around a single principle: the kernel passes sectors; it does not interpret them. All filesystem logic lives in userland services, isolated from the kernel by ION Rings and capability boundaries.

Components

• NexFS — The sovereign filesystem with content-addressable storage, DAG versioning, and a dual-axis design matrix
• Sovereign FSH — The filesystem hierarchy (/Cas, /Nexus, /Cell, /Bus, /Data) that replaces POSIX FHS
• Block Valve — The kernel's minimal storage interface

Design Philosophy

Traditional operating systems embed filesystem logic in the kernel. This means a malformed disk image or a bug in ext4 can crash the entire system.

Nexus inverts this:

Layer	Responsibility
Kernel (Block Valve)	Read/write sectors. That's it.
Userland (NexFS)	Parse superblocks, manage inodes, handle encryption, run CAS/DAG logic
Application	File open/read/write through Membrane POSIX shim or native ION channels

If NexFS crashes, the kernel is unaffected. The storage fiber restarts, recovers state from ProvChain, and continues.

Storage Classes

NexFS uses a dual-axis design matrix:

Axis 1 — Storage Class (how much hardware you have):

Class	Target	Example
Atom	Minimal flash/EEPROM	Mars rover sensor, IoT probe
Sovereign	Local disk	Laptop, NAS, home server
Archive	Cold storage	Backup vault, tape library

Axis 2 — Network Scope (how connected you are):

Scope	Connectivity	Feature Set
Local	Standalone	Core format only
Cluster	LAN peers	+ CAS deduplication, CDC sync
Chapter	WAN federation	+ DAG versioning, TimeWarp snapshots
Federation	Global mesh	+ Economic incentives, vouch ceremonies

The feature set scales up with both axes. An Atom/Local device runs the bare minimum format. A Sovereign/Federation device runs the full stack with CAS, CDC, DAG, TimeWarp, and economic incentives.

Build Flags

Storage features are controlled by compile-time flags:

nexfs_core        # Base format (always included)
nexfs_sovereign   # Sovereign extensions (CAS, CDC, DAG, TimeWarp)
nexfs_cluster     # Cluster sync and peer discovery
nexfs_chapter     # WAN federation
nexfs_federation  # Full mesh with economics

This ensures that a 256-byte sensor firmware doesn't carry DAG versioning code it will never use.