cyberdeck/docs/storage-architecture.md

Storage Architecture

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

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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

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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.

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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

# /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.

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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              │
└─────────────────────────────────────┘

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Backup Strategy

SD Card Imaging

# 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

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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.

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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