Đồng bộ WSL gốc (nâng cao)

⭐ Chương quan trọng nhất nếu bạn dùng WSL. Real performance numbers từ kinh nghiệm thực.

Vấn đề: Syncthing trên Windows đọc file WSL chậm

Nếu bạn add folder Windows Syncthing với path \\wsl.localhost\Ubuntu\home\<user>\projects (cross-OS), bạn sẽ gặp:

Folder: wsl-projects
Total scanned: 1.07 GB / 5 phút
Rate: ~33 MB/phút 🐌

24 GB folder ~= 12 giờ initial scan. Daily incremental sync rất chậm. File watcher unreliable.

Root cause: 9P protocol bridge

Windows Syncthing process
        ↓
  Đọc file qua 9P bridge (Windows ↔ WSL VM)  ← BOTTLENECK
        ↓
  WSL ext4 filesystem

9P Plan 9 protocol là cách Windows access WSL filesystem. Slow vì:

• Each file read = round-trip Windows → WSL VM → ext4 → response
• Per-file overhead lớn (~ms each) cho many small files
• Hash 24GB qua 9P = unbearable

Giải pháp: Cài Syncthing TRONG WSL Ubuntu

Trước:
  Windows Syncthing → 9P bridge → WSL ext4 (33 MB/min)

Sau:
  WSL Syncthing native → ext4 (3952 MB/min) — 120x faster

Trade-off: 2 Syncthing instances per machine (1 Windows + 1 WSL).

Tổng quan kiến trúc

PC machine                                Laptop machine
┌─────────────────────────────┐          ┌─────────────────────────────┐
│ Windows                      │          │ Windows                     │
│ ├─ Syncthing :8384 (BEP 22000)│        │ ├─ Syncthing :8384          │
│ │  ├─ ~/.claude/             │ ←────→  │ │  ├─ ~/.claude/            │
│ │  └─ Documents/             │          │ │  └─ Documents/            │
│ │                             │          │ │                            │
│ └─ WSL Ubuntu                │          │ └─ WSL Ubuntu               │
│    └─ Syncthing :8385        │          │    └─ Syncthing :8385       │
│       (BEP 22001)            │ ←────→  │       (BEP 22001)           │
│       └─ ~/projects/         │          │       └─ ~/projects/        │
└─────────────────────────────┘          └─────────────────────────────┘

4 Device IDs total (2 instances × 2 machines).

Bước 1: Bật mirrored networking cho WSL

Without mirrored mode, WSL VM có private NAT IP (172.x.x.x) — laptop’s WSL không reach PC’s WSL được.

Lưu ý

Mirrored networking (Windows 11 22H2+): WSL processes share Windows host network namespace. WSL services available on host LAN IP.

Edit C:\Users\<user>\.wslconfig trên cả 2 máy:

[wsl2]
networkingMode=mirrored
firewall=true
dnsTunneling=true
autoProxy=true

[experimental]
hostAddressLoopback=true

Restart WSL:

wsl --shutdown
# Wait 5s
wsl bash -c "hostname -I"
# Expect: shows host LAN IP (vd 192.168.1.14)

Cảnh báo

wsl --shutdown sẽ stop tất cả Docker containers + WSL processes.

Nếu bạn host services trong WSL (vd n8n, postgres), check restart: unless-stopped trong docker-compose để auto-restart sau wsl boot.

Downtime expected: 30-60 giây.

Bước 2: Cài Syncthing trong WSL Ubuntu

# Inside WSL Ubuntu
sudo apt update
sudo apt install -y syncthing

Bước 3: Cấu hình port khác Windows

Vấn đề: WSL share host network → port 22000 (BEP) + 8384 (GUI) đã dùng bởi Windows Syncthing → conflict.

Solution: change WSL Syncthing ports.

# Generate config with separate home dir
syncthing generate --home ~/.config/syncthing-wsl

# Change ports
sed -i 's|<address>127.0.0.1:8384</address>|<address>127.0.0.1:8385</address>|' ~/.config/syncthing-wsl/config.xml
sed -i 's|<listenAddress>default</listenAddress>|<listenAddress>tcp://0.0.0.0:22001</listenAddress><listenAddress>quic://0.0.0.0:22001</listenAddress>|' ~/.config/syncthing-wsl/config.xml
sed -i 's|<localAnnouncePort>21027|<localAnnouncePort>21028|' ~/.config/syncthing-wsl/config.xml

# Verify
grep -E "listenAddress|<address>|localAnnouncePort" ~/.config/syncthing-wsl/config.xml

Port allocation table:

Service	Windows Syncthing	WSL Syncthing
GUI Web UI	8384	8385
BEP sync (TCP+QUIC)	22000	22001
Local discovery	21027	21028

Bước 4: Khởi động daemon Syncthing trong WSL

nohup syncthing serve --home ~/.config/syncthing-wsl --no-browser > ~/syncthing-wsl.log 2>&1 &
sleep 5

# Verify
curl -s -o /dev/null -w "Web UI: HTTP %{http_code}\n" http://127.0.0.1:8385
# Expect: HTTP 200

Bước 5: Lấy Device ID của WSL

# From config.xml
grep -oE '<device id="[^"]+" name="[^"]*"' ~/.config/syncthing-wsl/config.xml | head -1

# Output (example):
# <device id="ABCD123-EFG456-IJKL789-..." name="My WSL"

Note Device ID này — sẽ dùng cho pairing.

Bước 6: Tự khởi động Syncthing khi WSL boot

Default WSL Syncthing không tự start sau wsl --shutdown. Add to startup:

# Add to ~/.bashrc hoặc ~/.zshrc
cat >> ~/.bashrc << 'EOF'

# Auto-start Syncthing WSL daemon (skip if already running)
if ! pgrep -f "syncthing.*syncthing-wsl" > /dev/null; then
  nohup syncthing serve --home ~/.config/syncthing-wsl --no-browser > ~/syncthing-wsl.log 2>&1 &
fi
EOF

Bước 7: Pair WSL Syncthing PC ↔ Laptop

Repeat Step 1-6 trên Laptop.

Sau đó pair:

1. Trên PC’s WSL Web UI http://127.0.0.1:8385:

   • Add Remote Device → paste Laptop’s WSL Device ID

2. Trên Laptop’s WSL Web UI:

   • Auto-detect notification → click Add Device, accept

3. Verify connection trong Web UI → Remote Devices section:

   • Status: Connected
   • Address: shows host LAN IP (vd 192.168.1.16:22001)
   • Type: TCP LAN hoặc QUIC

Bước 8: Thêm folder WSL để đồng bộ

8.1 Trên PC’s WSL Web UI → Add Folder

• Path: /home/<user>/projects (native ext4)
• Sharing: tick Laptop’s WSL device
• Ignore Patterns — critical cho code projects:

**/node_modules
**/dist
**/build
**/.next
**/out
**/.venv
**/venv
**/__pycache__
**/*.pyc
**/coverage
**/data
**/postgres-data
**/.docker
**/*.log
**/.cache
**/tmp
**/.env.local
.DS_Store
Thumbs.db

8.2 Laptop’s WSL Web UI → Accept folder offer

• Path: /home/<user>/projects (mirror PC)

8.3 Initial sync starts

Native ext4 reads = fast scan + transfer.

Số liệu tốc độ (đo thực tế)

Em đã measure thực tế setup AIWS production:

Metric	Windows reads WSL (9P)	WSL Native	Speedup
Initial scan rate	33 MB/phút	3952 MB/phút	120x faster
24 GB folder scan	~12 giờ	~6 phút	120x
Sync rate (LAN)	46 KiB/s	80-100 MB/s	~2000x
File watcher	Unreliable	Reliable	—

Xử lý sự cố đồng bộ WSL

Port conflict 22000

Windows Syncthing đã dùng 22000. WSL phải dùng 22001 — xem Step 3.

Verify với:

ss -tlnp | grep -E ":22000|:22001|:8384|:8385"

2 WSL không thấy nhau

Check mirrored networking active:

ip addr show | grep "inet "

Expect: thấy host LAN IP (192.168.x.x), KHÔNG phải 172.x (NAT).

Nếu vẫn 172.x → wsl --shutdown lại từ Windows, restart WSL.

Mirrored mode break network apps

Một số apps Windows có network conflict với mirrored mode. Test: ping google.com từ WSL.

Workaround: tạm disable mirrored, dùng port forwarding:

netsh interface portproxy add v4tov4 listenport=22001 listenaddress=0.0.0.0 connectport=22001 connectaddress=<WSL_IP>

Sync chậm dù đã native

Causes:

• Many small files (vd .git/objects/) — overhead per-file lớn
• Hash CPU bound (small VPS / weak CPU)
• Disk I/O slow (HDD instead of SSD)

Mitigation:

• Add ignore patterns rộng hơn
• Sync chỉ folders critical, skip rest

Bước tiếp theo

WSL native sync đã ready. Real-world use cases:

• Sync Claude Code state — conversations + skills
• Sync code projects — npm/pnpm projects
• AI agent prompts — autonomous setup