External Storage

Published

May 31, 2026

Modified

May 31, 2026

The Digitization Toolkit can save captured images to an external USB drive or SD card instead of the device’s internal storage. This is useful when digitizing large collections that would exceed the capacity of the built-in microSD card.

Experimental feature

This feature depends on operating-system-level disk operations. Compatibility varies by drive format and hardware. See Supported formats below. Do not rely on an external drive as your only copy of digitized material — always keep a backup.

How it works

When an external drive is activated, new projects are saved to a dtk-projects/ folder on that drive. Existing projects already stored on the internal card are unaffected and remain accessible. Only one external location can be active at a time.

Preparing the drive

Recommended format: exFAT

exFAT is the recommended format for external drives used with the toolkit. It is:

Compatible with Linux, Windows, and macOS (no drivers needed on any platform)
Supports files larger than 4 GB (important for high-resolution image sets)
Well-supported on Raspberry Pi OS

How to format a drive as exFAT

# Install the exFAT tools if not already present
sudo apt install exfatprogs

# Identify the drive (look for your USB device — e.g. /dev/sda2)
lsblk

# Format the partition (replace /dev/sdXN with your actual partition)
sudo mkfs.exfat /dev/sdXN

Caution

Double-check the device path with lsblk before running mkfs. Formatting the wrong partition will permanently erase its contents.

Open File Explorer and right-click the drive → Format…
Set File system to exFAT
Click Start

Open Disk Utility (Applications → Utilities → Disk Utility)
Select the drive in the left panel
Click Erase, set Format to ExFAT, then click Erase

Format compatibility summary

Format	Works with DTK	Notes
exFAT	✅ Recommended	Best cross-platform choice
ext4	✅ Supported	Linux-only; slightly faster
FAT32 (vfat)	✅ Supported	4 GB file size limit
NTFS	⚠️ May work	Requires `ntfs-3g`; not guaranteed
APFS	❌ Not supported	macOS-only filesystem
HFS+	❌ Not supported	macOS-only filesystem

Using external storage in the UI

Navigate to Configuración (the gear icon in the sidebar) and expand the Unidad de almacenamiento section.

Step 1 — Connect the drive

Plug the USB drive or SD card into the Raspberry Pi. The drive does not need to be mounted beforehand.

Step 2 — Mount the drive

The device list shows all detected partitions. Unmounted partitions have a Montar (Mount) button.

Find the partition you want to use in the list
Click Montar
The toolkit mounts the drive and the button changes to Activar

Step 3 — Activate the drive

Click Activar next to the mounted partition. The toolkit:

Creates a dtk-projects/ directory on the drive (if it does not exist)
Sets that directory as the active projects location
Shows a green activo badge on the device row and a banner confirming the active path

New projects created after this point are stored on the external drive.

Deactivating / reverting to internal storage

Click Restaurar predeterminado in the override banner to switch back to the internal storage. The external drive is not unmounted — existing projects on it remain intact and accessible.

Safely removing the drive

Before physically unplugging the drive:

If it is the active storage location, click Restaurar predeterminado first
Click Desmontar next to the partition
Wait for the success message
Unplug the drive

Important

Always click Desmontar before unplugging. Removing a drive while it is mounted can corrupt the filesystem and cause data loss.

Troubleshooting

Drive not appearing in the list: The toolkit only shows partitions on removable devices that are not part of the operating system. Try clicking Actualizar lista. If the drive still does not appear, check that it is properly connected and recognised by the OS (lsblk in a terminal).
“Montar” returns an error: The drive may use an unsupported format (APFS, HFS+) or require additional kernel modules (NTFS). Reformat the drive as exFAT and try again.
“Activar” fails with a permission error: This can happen on freshly formatted ext4 drives where the filesystem root is owned by root. The toolkit attempts a fallback using elevated privileges. If it still fails, reformat the drive as exFAT.
Drive mounted but read-only: Some drives enforce read-only mode when almost full or when the filesystem has errors. Check available space and run sudo fsck /dev/sdXN (with the drive unmounted) to repair any filesystem errors.