Time Machine Backups

While sharing, the device advertises itself as a Time Machine destination, so a Mac on the same network can back up to the drawer device. There is nothing to configure on the server side.

Setting up the Mac

Open System Settings → General → Time Machine and click Add Backup Disk…
Pick the "Time Machine" share on "NAS Reborn (device name)" from the list of available disks.
Sign in with a device account when asked.

The backup folder is created on the server automatically the first time the Mac connects. From then on it behaves like any other Time Machine disk, with hourly backups while the Mac is on the network and restores through the normal Time Machine browser or during migration to a new Mac.

Space to grow

The backup history of a Mac is usually larger than the internal storage of an old phone, so you should put the destination on a USB drive for anything more than a token backup. When a Mac first sets up Time Machine, the app offers to move the new backup folder onto a drive. The same move is available at any time from the screen of the folder and it keeps the share name and addresses, so the Mac keeps backing up to the same destination. See External Drives for adapters, power and formats. Every private folder the server shares appears in the destination picker on the Mac, so a folder added straight from a drive works too.

The free tier never squeezes backups. Storage limits apply to web and S3 serving only, and files arriving over SMB, including Time Machine, are never blocked. The backup folder does not count against the folder limit of the free tier either, and it is created for you the first time a Mac backs up. Time Machine manages its own space within the disk and thins old backups as the disk fills.

A backup is never a web page. A folder holding a Time Machine backup is a complete copy of somebody's Mac, so the server refuses every anonymous web request for it whatever its access level says, and there is no switch to change that. Your Mac, signed-in browsers and signed S3 clients reach it exactly as before.

Keeping backups reliable

A Time Machine backup is a long, stateful operation, and a target disappearing in the middle of a write is worse than one that was never there. Two habits keep the target trustworthy:

Keep NAS Reborn in front on the server device. Sharing pauses whenever the app leaves the screen, so use Guided Access or Single App Mode as described in Always-On Serving.
Keep the device plugged in, so a backup never dies from an empty battery.

A network Time Machine target on a spare phone is a fine everyday backup, and the watchdog tells you when it stops serving. For data you cannot afford to lose, follow the classic advice of keeping more than one backup in more than one place.