External Drives

A folder on a USB drive serves like any other folder, so the server's storage is not limited to what the phone shipped with. The right adapter and a little care about power make an old device with a big drive a very capable server.

Connecting a drive

If a drive shows up in the Files app, NAS Reborn can serve from it. Once it is mounted, use Add external directory… on the Content tab (or drag the folder in from Files) and pick a folder on the drive; it appears in the tree carrying the drive's name. Sharing an external folder on the network drive is free, like any other folder; serving it as a website or an S3 bucket is part of the Pro unlock. How they behave in the tree is covered in Folders, Access and Websites.

• USB-C devices connect the drive directly, or through a hub when the single port also needs to charge the device.
• Lightning devices need Apple's Lightning to USB 3 Camera Adapter. Despite the name it is a general USB port, and its second Lightning port takes the charger, so the device stays powered with the drive attached. Lightning runs at USB 2 speed (roughly 35 MB/s) on most of these devices: plenty for serving files, just patient work for the first big copy onto the drive.

Moving an existing folder onto a drive

A folder that already lives on the device can move: in its folder screen, choose Move to External Folder… and pick a folder on the drive. Everything is copied over, the drive then serves in the folder's place with the same share name, addresses and access level, and the copy on the device is removed.

The folder on the drive does not have to be empty. What is already in it stays, and files that are in both places with the same content are left where they are, so an interrupted move can simply be repeated. If the same file exists in both places with different content, nothing is copied: the app names the files it cannot reconcile, and the drive is left as it was.

This is also what the app offers when a Mac first sets up Time Machine, since backups outgrow internal storage quickly. If files change mid-copy, a running backup for example, the move rolls back and can be tried again later.

Powering the drive

An iPhone or iPad supplies only a few watts to accessories. A drive that needs more is refused by iOS with an "accessory uses too much power" message: flash sticks and SSDs are usually fine, while spinning hard drives often are not. Two reliable fixes:

• a drive with its own power supply, which asks nothing of the phone;
• a powered USB hub between device and drive. On USB-C, prefer a hub with power-delivery pass-through: the charger goes into the hub, and one chain both charges the device and powers the drive. On Lightning, the Camera Adapter's charging port plays that role, with a powered hub attached when one drive is not enough.

Formats

iOS mounts drives formatted as APFS, HFS+, exFAT or FAT32, with a single data partition. NTFS does not mount at all, not even read-only, so a Windows-formatted drive needs reformatting first; exFAT is the comfortable choice that both Windows and Mac read and write.

Unplugging and reattaching

Detach the drive, deliberately or by cable accident, and its folders show why they are unavailable, while web and S3 clients get a try-again-later answer that no sync client mistakes for deletion. Reattach the drive and serving resumes by itself; the server remembers its external folders across relaunches and reboots. Removing an external folder in the app only stops serving it, and the files on the drive are never touched.