# Storage Architecture

**Strategy:** SD card for boot/root, USB for data

---

## Design Principles

1. **Simplicity:** SD card boots out of the box, no U-Boot complexity
2. **Reliability:** Endurance-rated SD cards last longer
3. **Flexibility:** USB storage can be swapped/upgraded easily
4. **Cost:** Minimal investment, repurpose existing drives

---

## Layer 1: Boot/Root (MicroSD)

### Card Selection

| Attribute | Recommendation |
|-----------|----------------|
| Capacity | 64GB minimum, 128 GB preferred |
| Type | Endurance-rated or Industrial |
| Brands | SanDisk Endurance, Samsung PRO Endurance |

**Why endurance cards:**

Consumer SD cards are rated for bursts of writes (camera use). OS usage is constant logging, updates, cache writes. Endurance cards are rated for:

- 5000+ hours of continuous recording
- 1000+ write cycles per sector
- 5-10× longer lifespan than consumer cards

**Cost:**$10-15 for 64GB

### Boot Configuration

Default Orange Pi 5 boots from SD:

```
/dev/mmcblk0 (SD card)
├── /dev/mmcblk0p1  → /boot (fat32, ~200MB)
├── /dev/mmcblk0p2  → / (ext4, ~60GB)
└── /dev/mmcblk0p3  → /home (ext4, remaining)
```

Or single partition with separate mount points:

```
/dev/mmcblk0p2  → / (ext4, all space)
    /home        → bind mount or subdirectory
```

### Root-on-USB (Optional)

For faster I/O, copy root to USB SSD:

1. Boot from SD, insert USB SSD
2. `sudo rsync -ax / /mnt/usb/`
3. Edit `/boot/extlinux/extlinux.conf`:
   ```
   append root=/dev/sda1
   ```
4. Boot from USB, SD only handles bootloader

**Tradeoff:** More complexity, faster app loading.

---

## Layer 2: Data Storage (USB)

### Options

| Option | Speed | Cost | Notes |
|--------|-------|------|-------|
| USB flash drive | 100-150 MB/s | $12-20 | Cheap, limited endurance |
| USB 3.0 SATA enclosure | ~400 MB/s | $10-15 + drive | Reuse 2.5" drives |
| USB 3.0 NVMe enclosure | ~400 MB/s | $8-15 + drive | Compact, fast |
| USD 3.0 flash drive (fast) | 200-400 MB/s | $20-40 | Kingston DataTraveler, Samsung BAR |

### Recommendation

**USB 3.0 SATA enclosure with salvaged 2.5" SSD.**

If you have a spare 2.5" SATA SSD from another build/upgrade:
- Enclosure cost: $10-15
- Speed: ~400 MB/s (SATAIII limit over USB 3.0)
- Capacity: whatever the drive is

If no spare drive:
- USB 3.0 flash drive (128GB): $15-25
- Or NVMe enclosure ($10) + budget NVMe drive ($20-30)

### Mount Strategy

```bash
# /etc/fstab
UUID=<ssd-uuid>/mnt/data    ext4    defaults,noatime    0  2
/mnt/data/projects /home/jez/projects  none    bind    0  0
/mnt/data/media   /home/jez/media     none    bind    0  0
```

Mount on-demand or at boot, depending on use case.

---

## Storage Layout

```
┌─────────────────────────────────────┐
│  MicroSD Card (/dev/mmcblk0)       │
│  SanDisk Endurance 64GB             │
│  ├── /boot     (fat32, 200MB)       │
│  ├── /         (ext4, 25GB)         │
│  └── /home     (ext4, 38GB)         │
│      Basic config, small files      │
└─────────────────────────────────────┘

┌─────────────────────────────────────┐
│  USB SSD (/dev/sda)                 │
│  SATA or NVMe in USB 3.0 enclosure  │
│  ├── /mnt/data/projects             │
│  ├── /mnt/data/media                │
│  └── /mnt/data/backup               │
│      Mounted on-demand              │
└─────────────────────────────────────┘
```

---

## Backup Strategy

### SD Card Imaging

```bash
# Backup
sudo dd if=/dev/mmcblk0 of=cyberdeck-sd-backup.img bs=4M status=progress

# Restore
sudo dd if=cyberdeck-sd-backup.img of=/dev/mmcblk0 bs=4M status=progress
```

Or use **Pi Imager** / **BalenaEtcher** for GUI imaging.

### Data Backup

- Timeshift for system snapshots
- rsync to external drive
- Cloud sync for critical files

---

## Performance Expectations

| Operation | SD Card | USB SSD |
|-----------|---------|---------|
| Boot time | 8-12s | 5-8s (root-on-USB) |
| App launch | 1-3s | 0.5-1s |
| File read (1GB) | 40-90s | 3-5s |
| File write (1GB) | 60-120s | 3-5s |
| Random I/O | Slow | Fast |

**SD card is fine forOS and light use. USB SSD for anything I/O intensive.**

---

## Cost Summary

| Item | Low | High |
|------|-----|------|
| MicroSD 64GB Endurance | $10 | $15 |
| USB 3.0 SATA enclosure | $10 | $15 |
| (Assume spare SSD) | $0 | $0 |
| **Total** | **$20** | **$30** |

If no spare SSD:

| Item | Low | High |
|------|-----|------|
| MicroSD 64GB Endurance | $10 | $15 |
| USB 3.0 flash drive 128GB | $15 | $25 |
| **Total** | **$25** | **$40** |