[btrfs] Add role and migrate nix-book

Also switched from trying to override the `nixos` user to instead just
installing home-manager _into_ the `nixos` user. It felt a bit like
fighting the tide otherwise.

build-liveusb.sh

@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+
+# Build Live USB ISO from flake configuration
+# Creates an uncompressed ISO suitable for Ventoy and other USB boot tools
+
+set -e
+
+echo "Building Live USB ISO..."
+nix build .#nixosConfigurations.live-usb.config.system.build.isoImage --show-trace
+
+if [ -f "./result/iso/"*.iso ]; then
+    iso_file=$(ls ./result/iso/*.iso)
+    echo "✅ Build complete!"
+    echo "📁 ISO location: $iso_file"
+    echo "💾 Ready for Ventoy or dd to USB"
+else
+    echo "❌ Build failed - no ISO file found"
+    exit 1
+fi

flake.nix

@@ -74,6 +74,22 @@
       ];
     };
 
+    # Live USB ISO configuration
+    nixosConfigurations.live-usb = nixpkgs.lib.nixosSystem rec {
+      system = "x86_64-linux";
+      modules = baseModules ++ [
+        ./machines/live-usb/configuration.nix
+        {
+          home-manager.users.nixos = { ... }: {
+            imports = [ ./home/home.nix ];
+            home.username = nixpkgs.lib.mkForce "nixos";
+            home.homeDirectory = nixpkgs.lib.mkForce "/home/nixos";
+          };
+          home-manager.extraSpecialArgs = { inherit system; };
+        }
+      ];
+    };
+
     homeConfigurations."johno" = inputs.home-manager.lib.homeManagerConfiguration {
       pkgs = inputs.nixpkgs.legacyPackages."x86_64-linux";
       modules = [

machines/live-usb/configuration.nix

@@ -0,0 +1,89 @@
+# Live USB ISO configuration for recovery and installation
+{ pkgs, modulesPath, ... }:
+
+{
+  imports = [
+    # Use minimal installation CD as base
+    (modulesPath + "/installer/cd-dvd/installation-cd-minimal.nix")
+  ];
+
+  # Use roles structure for consistent configuration
+  roles = {
+    audio.enable = true;
+    bluetooth.enable = true;
+    desktop = {
+      enable = true;
+      kde = true;
+      x11 = true;
+      wayland = true;
+      sddm = true;
+    };
+  };
+
+  # Allow unfree packages for broader hardware support
+  nixpkgs.config.allowUnfree = true;
+
+  # Essential packages for system recovery and installation
+  environment.systemPackages = with pkgs; [
+    # Text editors
+    neovim
+    nano
+    
+    # System tools
+    git
+    curl
+    wget
+    htop
+    tree
+    lsof
+    strace
+    
+    # Filesystem tools
+    btrfs-progs
+    e2fsprogs
+    xfsprogs
+    ntfs3g
+    dosfstools
+    
+    # Network tools
+    networkmanager
+    wirelesstools
+    
+    # Hardware tools
+    pciutils
+    usbutils
+    smartmontools
+    
+    # Archive tools
+    unzip
+    p7zip
+    
+    # Development tools (for quick fixes)
+    gcc
+    binutils
+  ];
+
+  # Enable NetworkManager for easy wifi setup
+  networking.networkmanager.enable = true;
+  
+  # Enable SSH daemon for remote access
+  services.openssh = {
+    enable = true;
+    settings = {
+      PermitRootLogin = "yes";
+      PasswordAuthentication = true;
+    };
+  };
+
+  # ISO customization
+  isoImage = {
+    volumeID = "NIXOS-LIVE";
+  };
+
+  # Enable some useful services
+  services.udisks2.enable = true; # For mounting USB drives
+
+  # Hardware support
+  hardware.enableAllFirmware = true;
+  hardware.enableRedistributableFirmware = true;
+}

machines/nix-book/configuration.nix

@@ -39,6 +39,7 @@
 
   boot.kernelPackages = pkgs.linuxPackages_latest;
 
+
   # Enable networking
   networking.networkmanager.enable = true;
 

machines/nix-book/hardware-configuration.nix

@@ -10,15 +10,27 @@
 
   boot.initrd.availableKernelModules = [ "xhci_pci" "thunderbolt" "vmd" "nvme" "sdhci_pci" ];
   boot.initrd.kernelModules = [ ];
+  boot.initrd.luks.devices."luks-4126fbd4-bd09-4ece-af0d-6fff414c21b3".device = "/dev/disk/by-uuid/4126fbd4-bd09-4ece-af0d-6fff414c21b3";
   boot.kernelModules = [ "kvm-intel" ];
   boot.extraModulePackages = [ ];
 
-  fileSystems."/" =
-    { device = "/dev/disk/by-uuid/bd396529-e2c4-47cb-b844-8d6ed841f81a";
-      fsType = "ext4";
+  roles.btrfs = {
+    enable = true;
+    filesystems."/dev/disk/by-uuid/223a44e5-91e2-4272-830e-129166042a1d" = {
+      mountpoints = {
+        "/" = {
+          compression = "zstd";
+          extraOptions = [ "noatime" ];
+        };
+      };
+      scrub.enable = true;
+      deduplication = {
+        enable = true;
+        hashTableSizeMB = 32;
+        verbosity = "err";
+      };
     };
-
-  boot.initrd.luks.devices."luks-4126fbd4-bd09-4ece-af0d-6fff414c21b3".device = "/dev/disk/by-uuid/4126fbd4-bd09-4ece-af0d-6fff414c21b3";
+  };
 
   fileSystems."/boot" =
     { device = "/dev/disk/by-uuid/7A0B-CF88";

machines/nix-book/nixbook-btrfs-migration.md

@@ -0,0 +1,223 @@
+# NixBook ext4 to btrfs Migration Guide
+
+## Overview
+This guide converts your nixbook machine from ext4 to btrfs with zstd compression and beesd deduplication while preserving your LUKS encryption and all data.
+
+## Current System Info
+- **Hostname**: nix-book
+- **Root filesystem**: ext4 on `/dev/disk/by-uuid/bd396529-e2c4-47cb-b844-8d6ed841f81a`
+- **Encryption**: LUKS with two devices configured
+- **Current usage**: 138GB used / 225GB total (65% full)
+- **Free space**: 76GB available (sufficient for conversion)
+
+## Pre-Migration Checklist
+
+### 1. Create Full System Backup (CRITICAL)
+```bash
+# Boot from NixOS live USB
+# Mount encrypted filesystem
+cryptsetup luksOpen /dev/disk/by-uuid/4126fbd4-bd09-4ece-af0d-6fff414c21b3 luks-nixbook
+mount /dev/mapper/luks-nixbook /mnt
+
+# Create backup to external drive (adjust target as needed)
+rsync -avxHAX --progress /mnt/ /path/to/backup/nixbook-backup/
+```
+
+### 2. Verify Configuration Changes
+The following files have been updated for btrfs:
+- `machines/nix-book/configuration.nix` - Added beesd service
+- `machines/nix-book/hardware-configuration.nix` - Changed fsType to btrfs with compression
+
+## Migration Process
+
+### Phase 1: Boot to Live Environment
+1. **Create NixOS live USB**:
+   ```bash
+   # Download latest NixOS ISO
+   # Flash to USB drive
+   dd if=nixos-minimal-xx.xx-x86_64-linux.iso of=/dev/sdX bs=4M status=progress
+   ```
+
+2. **Boot from live USB** and ensure you can access the encrypted drives
+
+### Phase 2: Filesystem Conversion
+3. **Unlock LUKS volumes**:
+   ```bash
+   cryptsetup luksOpen /dev/disk/by-uuid/4126fbd4-bd09-4ece-af0d-6fff414c21b3 luks-nixbook
+   cryptsetup luksOpen /dev/disk/by-uuid/b614167b-9045-4234-a441-ac6f60a96d81 luks-nixbook2
+   ```
+
+4. **Check filesystem before conversion**:
+   ```bash
+   fsck.ext4 -f /dev/mapper/luks-nixbook
+   ```
+
+5. **Convert ext4 to btrfs** (this preserves all data):
+   ```bash
+   # Install btrfs-progs if not available
+   nix-shell -p btrfs-progs
+
+   # Convert the filesystem (takes 15-45 minutes depending on data)
+   btrfs-convert /dev/mapper/luks-nixbook
+   
+   # Verify conversion succeeded
+   mount /dev/mapper/luks-nixbook /mnt
+   ls -la /mnt  # Should show your normal filesystem
+   btrfs filesystem show /mnt
+   ```
+
+6. **Get new filesystem UUID** (may have changed):
+   ```bash
+   blkid /dev/mapper/luks-nixbook
+   # Note the new UUID if it changed
+   ```
+
+### Phase 3: Configuration Update
+7. **Mount and chroot into system**:
+   ```bash
+   mount -o compress=zstd,noatime /dev/mapper/luks-nixbook /mnt
+   mount /dev/disk/by-uuid/7A0B-CF88 /mnt/boot
+   nixos-enter --root /mnt
+   ```
+
+8. **Update hardware-configuration.nix** if UUID changed:
+   ```bash
+   # Edit /etc/nixos/hardware-configuration.nix if needed
+   # Update the UUID in fileSystems."/" section
+   ```
+
+9. **Rebuild system with btrfs configuration**:
+   ```bash
+   cd /home/johno/nixos-configs
+   nixos-rebuild switch --flake .#nix-book
+   ```
+
+### Phase 4: Enable Compression and Deduplication
+10. **Reboot into new btrfs system**:
+    ```bash
+    exit  # Exit chroot
+    umount -R /mnt
+    reboot
+    ```
+
+11. **Verify btrfs is working**:
+    ```bash
+    mount | grep btrfs
+    btrfs filesystem usage /
+    ```
+
+12. **Enable and start beesd**:
+    ```bash
+    systemctl status beesd-root
+    systemctl start beesd-root
+    systemctl enable beesd-root
+    ```
+
+13. **Force compression on existing files** (optional but recommended):
+    ```bash
+    # This will compress existing files with zstd
+    btrfs filesystem defragment -r -czstd /
+    ```
+
+## Post-Migration Verification
+
+### Check System Health
+```bash
+# Verify btrfs health
+btrfs scrub start /
+btrfs scrub status /
+
+# Check compression effectiveness
+compsize /
+
+# Monitor beesd deduplication
+journalctl -u beesd-root -f
+
+# Check filesystem usage
+btrfs filesystem usage /
+df -h /
+```
+
+### Performance Monitoring
+```bash
+# Monitor beesd hash table
+ls -lh /.beeshash
+
+# Check compression ratio over time
+compsize /home /nix /var
+```
+
+## Expected Benefits
+
+### Space Savings
+- **Compression**: 20-30% reduction in disk usage from zstd
+- **Deduplication**: Additional 10-20% savings on duplicate files
+- **Combined**: Potentially 30-40% total space savings
+
+### Performance Impact
+- **Compression**: Minimal CPU overhead, often improves I/O performance
+- **Deduplication**: Background process, minimal impact during normal use
+- **Overall**: Should be neutral to positive performance impact
+
+## Rollback Plan (Emergency)
+
+If something goes wrong:
+
+1. **Boot from live USB**
+2. **Restore from backup**:
+   ```bash
+   cryptsetup luksOpen /dev/disk/by-uuid/4126fbd4-bd09-4ece-af0d-6fff414c21b3 luks-nixbook
+   mkfs.ext4 /dev/mapper/luks-nixbook
+   mount /dev/mapper/luks-nixbook /mnt
+   rsync -avxHAX --progress /path/to/backup/nixbook-backup/ /mnt/
+   ```
+3. **Restore original hardware-configuration.nix** with ext4 settings
+4. **Rebuild and reboot**
+
+## Troubleshooting
+
+### Common Issues
+
+**"Device busy" during conversion**:
+- Ensure no processes are accessing the filesystem
+- Check with `lsof` and `fuser`
+
+**UUID changed after conversion**:
+- Update hardware-configuration.nix with new UUID
+- Regenerate initrd: `nixos-rebuild switch`
+
+**Beesd service fails to start**:
+- Check disk space for hash table
+- Verify filesystem is btrfs: `mount | grep btrfs`
+- Check logs: `journalctl -u beesd-root`
+
+**Boot issues after conversion**:
+- Boot from live USB
+- Check /boot partition is mounted correctly
+- Verify LUKS UUIDs match in configuration
+- Rebuild bootloader: `nixos-rebuild switch --install-bootloader`
+
+## Maintenance
+
+### Regular Tasks
+```bash
+# Monthly scrub (checks for corruption)
+btrfs scrub start /
+
+# Monitor compression effectiveness
+compsize /
+
+# Check beesd deduplication status
+systemctl status beesd-root
+```
+
+### Space Management
+```bash
+# Balance filesystem (defragments and optimizes)
+btrfs balance start -dusage=50 /
+
+# Check for space issues
+btrfs filesystem usage /
+```
+
+This migration preserves all your data while gaining the benefits of modern btrfs features including transparent compression and automatic deduplication.

nixos-steam-dual-boot-plan.md

@@ -1,333 +0,0 @@
-# NixOS Steam Dual Boot Implementation Plan (Btrfs + Beesd Edition)
-
-## Goals & Motivations
-
-### Primary Goals
-1. **Eliminate storage waste**: Avoid duplicating terabytes of Steam games across Windows and NixOS
-2. **Minimize maintenance overhead**: Create a solution that works reliably without constant tweaking
-3. **Preserve Windows stability**: Ensure Windows Steam functionality remains unaffected by the dual-boot setup
-4. **Maintain gaming performance**: No significant performance degradation on either OS
-
-### Secondary Goals
-- **Seamless game access**: Games should be available on both OSes without manual intervention
-- **Update compatibility**: Game updates from either OS should be usable by both
-- **Future-proof architecture**: Solution should be extensible and maintainable
-- **Multi-user support**: Handle 3 Windows users sharing libraries, with 1 user also using Linux
-
-## Architectural Overview
-
-### The Problem with Previous Approaches
-
-**Shared NTFS Library (Traditional)**:
-- ❌ Proton creates files with colons, corrupting NTFS
-- ❌ Requires fragile symlinks that Windows can break
-- ❌ Permission issues plague the setup
-- ❌ Valve officially discourages this approach
-
-**Complex Symlink Management**:
-- ❌ Requires custom scripts and maintenance
-- ❌ Fragile edge cases with Steam updates
-- ❌ Potential compatibility issues with Proton and anti-cheat
-
-**Separate Libraries**:
-- ❌ Wastes terabytes of storage
-- ❌ Games must be installed twice
-- ❌ No benefit from either OS's installations
-
-### Our Solution: Btrfs + Beesd Automatic Deduplication
-
-```
-Windows Steam → /steam/windows/ (btrfs via WinBtrfs driver)
-                     ↓
-Linux Steam   → /steam/linux/  (native btrfs)
-                     ↓
-               [beesd automatically deduplicates identical files]
-```
-
-**Key Insight**: Let each Steam installation work independently, rely on proven btrfs deduplication technology to eliminate duplicate storage automatically.
-
-## Architecture Deep Dive
-
-### Component 1: Shared Btrfs Filesystem
-
-**Purpose**: Single high-performance filesystem for all game storage
-- **Location**: `/steam` (dedicated btrfs partition)
-- **Contents**: 
-  - `/steam/windows/` - Windows Steam library
-  - `/steam/linux/` - Linux Steam library
-- **Access**: Native on Linux, WinBtrfs driver on Windows
-
-**Why this satisfies our goals**:
-- ✅ **Automatic deduplication**: Beesd handles duplicate elimination transparently
-- ✅ **No maintenance**: Zero custom scripts or symlink management
-- ✅ **Independent operation**: Each Steam installation works normally
-- ✅ **Performance**: Optimized mount options for gaming workloads
-
-### Component 2: Beesd Deduplication Service
-
-**Purpose**: Automatic background deduplication of game files
-
-**Core Functionality**:
-- Continuously scans `/steam` for duplicate blocks
-- Automatically deduplicates identical files between `/steam/windows/` and `/steam/linux/`
-- Operates transparently - games never know deduplication is happening
-- Handles common duplicates: DirectX runtimes, Visual C++ redistributables, game engines, shared assets
-
-**Expected Efficiency**:
-- **40-70% storage savings** for typical game libraries
-- **Common targets**: Unity/Unreal engine files, shared libraries, identical texture assets
-- **Real-time operation**: New duplicates eliminated automatically
-
-### Component 3: WinBtrfs Driver Integration
-
-**Purpose**: Provide Windows with native btrfs read/write access
-
-```nix
-# No special configuration needed - standard btrfs mount
-fileSystems."/steam" = {
-  device = "/dev/disk/by-uuid/YOUR-BTRFS-UUID";
-  fsType = "btrfs";
-  options = [ 
-    "noatime"    # Don't update access times - major gaming performance boost
-    "ssd"        # SSD optimizations
-  ];
-};
-```
-
-**Windows Requirements**:
-- Install WinBtrfs driver (https://github.com/maharmstone/btrfs)
-- Configure Steam library path to point to `/steam/windows/`
-- No special configuration needed - works like any other drive
-
-### Component 4: Beesd Configuration
-
-**Purpose**: Optimized deduplication for gaming workloads
-
-```nix
-services.beesd.filesystems = {
-  steam = {
-    spec = "/steam";
-    hashTableSizeMB = 512;   # Sized for ~4TB of game data (128MB per TB)
-    verbosity = "err";       # Only show actual problems
-  };
-};
-```
-
-**Hash Table Storage**:
-- Stored as file: `/steam/.beeshash`
-- 512MB handles up to 4TB of game data efficiently (beesd recommends 128MB per TB)
-- Loaded into RAM on-demand, not all resident simultaneously
-- Smaller hash table = better performance and less disk usage
-
-## Partition Strategy
-
-### 4-Partition Architecture
-
-1. **Windows Boot Partition** (NTFS) - *Existing*
-   - Standard Windows system drive
-   - Unchanged from current setup
-
-2. **Linux Boot Partition** (btrfs/ext4) - *New*
-   - NixOS system installation
-   - Standard Linux root filesystem
-
-3. **Shared Steam Library** (btrfs) - *New*
-   - `/steam/windows/` - Windows Steam library
-   - `/steam/linux/` - Linux Steam library
-   - Automatic beesd deduplication
-
-4. **Legacy Windows Steam** (NTFS) - *Existing, Optional*
-   - Keep for anti-cheat games that may not work on btrfs
-   - Can be eliminated if all games work on btrfs
-   - Provides fallback option during testing
-
-### Multi-User Considerations
-
-**Current Setup**: 3 Windows users sharing Steam libraries
-**Migration Strategy**: 
-- Other Windows users continue using existing NTFS library
-- Primary user (johno) experiments with btrfs library
-- Easy rollback: point Steam back to NTFS if issues arise
-- Gradual migration as confidence builds
-
-## Implementation Strategy
-
-### Phase 1: Base Setup
-
-1. **Partition Creation**:
-   - Create new btrfs partition for `/steam` (recommend 2TB+ for modern libraries)
-   - Install NixOS on separate Linux boot partition
-   - Keep existing Windows partitions untouched
-
-2. **NixOS Configuration**:
-   ```nix
-   fileSystems."/steam" = {
-     device = "/dev/disk/by-uuid/YOUR-BTRFS-UUID";
-     fsType = "btrfs";
-     options = [ "noatime" "ssd" ];
-   };
-
-   services.beesd.filesystems = {
-     steam = {
-       spec = "/steam";
-       hashTableSizeMB = 512;   # 128MB per TB recommended
-       verbosity = "err";
-     };
-   };
-   ```
-
-3. **Windows Setup**:
-   - Install WinBtrfs driver
-   - Add Steam library pointing to `/steam/windows/`
-   - Test with a few small games initially
-
-### Phase 2: Gradual Migration
-
-1. **Safe Game Testing**:
-   - Start with single-player games
-   - Test save game compatibility
-   - Verify performance matches NTFS installation
-
-2. **Anti-Cheat Evaluation**:
-   - Test multiplayer games progressively
-   - Document which games work on btrfs vs require NTFS
-   - Keep problematic games on legacy NTFS partition
-
-3. **Deduplication Verification**:
-   - Monitor beesd logs for successful deduplication
-   - Use `btrfs filesystem du /steam` to verify space savings
-   - Benchmark game loading times vs separate installations
-
-### Phase 3: Optimization
-
-1. **Performance Tuning**:
-   - Monitor btrfs performance under gaming workloads
-   - Adjust mount options if needed
-   - Optimize beesd parameters based on actual usage
-
-2. **Monitoring Setup**:
-   - SystemD service monitoring for beesd
-   - Disk space alerts for `/steam` partition
-   - Basic health checks for WinBtrfs stability
-
-## Trade-offs and Considerations
-
-### Advantages
-
-**Storage Efficiency**:
-- ✅ 40-70% storage savings through automatic deduplication
-- ✅ No manual intervention required
-- ✅ Works with any game installation method
-
-**Simplicity**:
-- ✅ No custom scripts to maintain
-- ✅ No symlink complexity
-- ✅ Standard Steam library management on both OSes
-
-**Reliability**:
-- ✅ Each Steam installation completely independent
-- ✅ Btrfs and beesd are mature, proven technologies
-- ✅ Graceful degradation if deduplication fails
-
-**Performance**:
-- ✅ Optimized mount options for gaming
-- ✅ No compression overhead
-- ✅ Native filesystem performance on both OSes
-
-### Limitations
-
-**Windows Dependencies**:
-- ⚠️ Requires WinBtrfs third-party driver
-- ⚠️ Driver updates needed with major Windows releases
-- ⚠️ Potential compatibility issues with some anti-cheat systems
-
-**Complexity Trade-offs**:
-- ⚠️ More partitions to manage than single-filesystem approach
-- ⚠️ Beesd adds background CPU/disk usage (minimal but present)
-- ⚠️ Hash table requires disk space (512MB for large libraries)
-
-**Platform Compatibility**:
-- ⚠️ Some games may prefer NTFS for maximum compatibility
-- ⚠️ Anti-cheat systems may flag non-NTFS installations
-- ⚠️ WinBtrfs stability depends on third-party development
-
-### Risk Mitigation
-
-**Backup Strategy**:
-- Regular btrfs snapshots of `/steam` partition
-- Keep legacy NTFS Steam library as fallback
-- Steam's built-in backup/restore for critical games
-
-**Fallback Options**:
-- Easy to revert games to NTFS library if needed
-- Linux can install games locally if `/steam` partition fails
-- Independent operation means failure in one OS doesn't affect the other
-
-**Monitoring**:
-- SystemD service status for beesd
-- Disk space monitoring for early warning
-- Game launch testing after major updates
-
-## Expected Outcomes
-
-### Immediate Benefits
-- **40-70% storage savings** for typical game libraries
-- **Zero maintenance** after initial setup
-- **Identical performance** to native installations
-- **Future-proof** architecture using standard technologies
-
-### Long-term Benefits
-- **Automatic optimization**: New games deduplicated without intervention
-- **Simplified management**: One shared library instead of separate installations
-- **Technology leverage**: Benefits from ongoing btrfs and beesd improvements
-
-### Success Metrics
-- ✅ Games launch successfully from both OSes
-- ✅ Save games work correctly on both platforms
-- ✅ Updates from either OS don't break the other
-- ✅ Storage usage 40-70% less than separate libraries
-- ✅ No performance degradation vs native installations
-- ✅ Anti-cheat compatibility acceptable for target games
-
-### Monitoring and Maintenance
-
-**Automated Monitoring**:
-```nix
-# Add to NixOS configuration for basic monitoring
-systemd.services.steam-health-check = {
-  description = "Check Steam partition and beesd health";
-  serviceConfig = {
-    Type = "oneshot";
-    ExecStart = pkgs.writeScript "steam-health" ''
-      #!/bin/bash
-      # Check beesd service status
-      systemctl is-active beesd-steam >/dev/null || echo "WARN: beesd not running"
-      
-      # Check disk space
-      USAGE=$(df /steam | tail -1 | awk '{print $5}' | sed 's/%//')
-      [ "$USAGE" -gt 90 ] && echo "WARN: Steam partition >90% full"
-      
-      # Verify both directories exist
-      [ ! -d "/steam/windows" ] && echo "ERROR: Windows Steam directory missing"
-      [ ! -d "/steam/linux" ] && echo "ERROR: Linux Steam directory missing"
-    '';
-  };
-};
-
-systemd.timers.steam-health-check = {
-  wantedBy = [ "timers.target" ];
-  timerConfig = {
-    OnCalendar = "daily";
-    Persistent = true;
-  };
-};
-```
-
-## Implementation Files Needed
-
-1. **NixOS Configuration Addition** - Add to existing machine config
-2. **WinBtrfs Installation Guide** - Windows setup instructions  
-3. **Migration Checklist** - Step-by-step game migration process
-4. **Troubleshooting Guide** - Common issues and solutions
-
-This architecture provides maximum storage efficiency with minimal complexity, leveraging proven technologies instead of custom solutions. The automatic nature of btrfs deduplication eliminates the maintenance overhead of complex symlink management while providing excellent storage savings.

roles/btrfs/default.nix

@@ -0,0 +1,168 @@
+{ lib, config, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.roles.btrfs;
+in
+{
+  options.roles.btrfs = {
+    enable = mkEnableOption "Enable btrfs filesystem management";
+    
+    filesystems = mkOption {
+      type = types.attrsOf (types.submodule {
+        options = {
+          # Filesystem-level maintenance options
+          scrub = {
+            enable = mkOption { 
+              type = types.bool; 
+              default = true;
+              description = "Enable automatic scrubbing for this filesystem";
+            };
+            interval = mkOption { 
+              type = types.str; 
+              default = "weekly";
+              description = "Scrub interval (systemd timer format)";
+            };
+          };
+          deduplication = {
+            enable = mkOption { 
+              type = types.bool; 
+              default = false;
+              description = "Enable beesd deduplication for this filesystem";
+            };
+            hashTableSizeMB = mkOption { 
+              type = types.int; 
+              default = 1024;
+              description = "Hash table size in MB (should be multiple of 16)";
+            };
+            verbosity = mkOption { 
+              type = types.str; 
+              default = "info";
+              description = "Logging verbosity level";
+            };
+          };
+          balance = {
+            enable = mkOption { 
+              type = types.bool; 
+              default = false;
+              description = "Enable periodic balance operations";
+            };
+            interval = mkOption { 
+              type = types.str; 
+              default = "monthly";
+              description = "Balance interval (systemd timer format)";
+            };
+            dataUsage = mkOption { 
+              type = types.int; 
+              default = 50;
+              description = "Data usage threshold for balance";
+            };
+            metadataUsage = mkOption { 
+              type = types.int; 
+              default = 50;
+              description = "Metadata usage threshold for balance";
+            };
+          };
+          
+          # Mountpoint-based configuration
+          mountpoints = mkOption {
+            type = types.attrsOf (types.submodule {
+              options = {
+                subvolume = mkOption { 
+                  type = types.nullOr types.str; 
+                  default = null;
+                  description = "Subvolume name. If null, uses default subvolume.";
+                };
+                compression = mkOption { 
+                  type = types.str; 
+                  default = "zstd";
+                  description = "Compression algorithm (zstd, lzo, lz4, none)";
+                };
+                autodefrag = mkOption { 
+                  type = types.bool; 
+                  default = false;
+                  description = "Enable automatic defragmentation";
+                };
+                extraOptions = mkOption { 
+                  type = types.listOf types.str; 
+                  default = [];
+                  description = "Additional mount options";
+                };
+              };
+            });
+            default = {};
+            description = "Mountpoint configurations for this filesystem";
+          };
+        };
+      });
+      default = {};
+      description = "Btrfs filesystems configuration";
+    };
+  };
+
+  config = mkIf cfg.enable {
+    # Generate fileSystems configuration from mountpoints
+    fileSystems = mkMerge (flatten (mapAttrsToList (device: fsCfg:
+      mapAttrsToList (mountpoint: mountCfg:
+        {
+          ${mountpoint} = {
+            device = device;
+            fsType = "btrfs";
+            options = 
+              (optional (mountCfg.subvolume != null) "subvol=${mountCfg.subvolume}") ++
+              [ "compress=${mountCfg.compression}" ] ++
+              (optional mountCfg.autodefrag "autodefrag") ++
+              mountCfg.extraOptions;
+          };
+        }
+      ) fsCfg.mountpoints
+    ) cfg.filesystems));
+    
+    # Configure scrub service using NixOS built-in
+    services.btrfs.autoScrub = mkIf (any (fs: fs.scrub.enable) (attrValues cfg.filesystems)) {
+      enable = true;
+      interval = "weekly"; # TODO: Make this configurable per filesystem
+      fileSystems = attrNames (filterAttrs (_: fs: fs.scrub.enable) cfg.filesystems);
+    };
+    
+    # Configure beesd for filesystems with deduplication enabled
+    services.beesd.filesystems = mapAttrs' (device: fsCfg: 
+      nameValuePair (replaceStrings ["/"] ["_"] (replaceStrings ["-"] ["_"] device)) {
+        spec = device;
+        hashTableSizeMB = fsCfg.deduplication.hashTableSizeMB;
+        verbosity = fsCfg.deduplication.verbosity;
+      }
+    ) (filterAttrs (_: fs: fs.deduplication.enable) cfg.filesystems);
+    
+    # Custom balance services for filesystems with balance enabled
+    systemd.services = mkMerge (mapAttrsToList (device: fsCfg: mkIf fsCfg.balance.enable {
+      "btrfs-balance-${replaceStrings ["/"] ["-"] (replaceStrings ["-"] ["_"] device)}" = {
+        description = "Balance btrfs filesystem ${device}";
+        script = ''
+          ${pkgs.btrfs-progs}/bin/btrfs balance start \
+            -dusage=${toString fsCfg.balance.dataUsage} \
+            -musage=${toString fsCfg.balance.metadataUsage} \
+            ${device}
+        '';
+        serviceConfig = {
+          Type = "oneshot";
+          Nice = 19;
+          IOSchedulingClass = "idle";
+        };
+      };
+    }) cfg.filesystems);
+    
+    # Balance timers
+    systemd.timers = mkMerge (mapAttrsToList (device: fsCfg: mkIf fsCfg.balance.enable {
+      "btrfs-balance-${replaceStrings ["/"] ["-"] (replaceStrings ["-"] ["_"] device)}" = {
+        description = "Periodic balance for ${device}";
+        wantedBy = [ "timers.target" ];
+        timerConfig = {
+          OnCalendar = fsCfg.balance.interval;
+          Persistent = true;
+        };
+      };
+    }) cfg.filesystems);
+  };
+}

roles/default.nix

@@ -6,6 +6,7 @@ with lib;
   imports = [
     ./audio
     ./bluetooth
+    ./btrfs
     ./desktop
     ./kodi
     ./nfs-mounts