Short answer
Each AmberTime task keeps its backup record on the current device. Later scans compare the source against that record and skip items already recorded as completed for the same task. This makes repeat iPhone photo backups to USB or external SSD incremental.
When this is useful
Incremental backup is useful for large iPhone libraries because the first backup may be big, but later backups should not start over. It also helps creators keep separate sources organized: one task for the Photo Library, one for DJI footage, one for downloads, and another for project folders.
For old-photo archiving, date-range tasks can also stay incremental. For example, a task for photos before 2024 can be run again later without recopying items already recorded as backed up.
What AmberTime does
- Scans identifiers first before fetching full details for new Photo Library items.
- Records successful backups per source and asset key.
- Skips files that are already known to be backed up for that task.
- Uses temporary .part files for in-progress writes.
- Allows multiple independent tasks for different sources.
What happens to edits, deleted files, and interrupted transfers?
AmberTime skips Photo Library items recorded as completed for the same task. Editing an already-backed-up photo does not trigger a fresh export. Deleting a source item does not delete its drive copy. Files folder changes use file attributes, and same-size edits may be skipped; this is not versioned or mirror backup.
Reconnect the drive and run the task again. Items recorded as completed are skipped; an unfinished file restarts from the beginning, not from its last byte. Writes use temporary .part files before finalization. Cleanup is best effort, so a disconnect or forced quit may leave a .part file; it is discarded before retrying that file.
AmberTime requests limited background time when you switch apps or lock the screen. iOS decides how much time is available; uninterrupted background backup is not guaranteed. If iOS pauses the task, return to AmberTime and start it manually. Completed items are skipped and the interrupted file restarts from the beginning. Keep large backups in the foreground.
Read the full backup behavior and limitations, including deletion and re-addition, on-device records, and Files folder matching.
Things to know
Backup task records are stored on the current device. A fresh install, a new task, or another device does not automatically import that state from the drive. Existing files may be reused when the expected path and size match, but this is not content verification or shared cross-device backup history.
AmberTime does not delete source photos or folders after backup. Cleanup remains a manual user choice after the archive is verified.