MacSnapshotGUIDE · LOCAL COPIES
Sync vs backup: what happens to changed and deleted files?
See how sync, an updated backup and version history handle deletions and overwrites. Plan a separate copy without assuming every backup keeps old versions.
Sync helps you work across devices
Synchronization keeps files consistent across locations. That helps when you work on two computers, but it can also pass along an unwanted edit. Deletion behavior depends on the tool and its settings. Having the same file on two devices does not mean you have an earlier version.
An updated copy puts files in a separate location
MacSnapshotBackup copies in one direction: from your Mac to the destination drive. Removing a file from the copy does not remove its source; if the source still exists, a later backup can copy it again. Removing a source does not automatically delete its backed-up file.
This helps with a deleted source but does not preserve every previous set of contents. A detected edit overwrites the old copy. A rename may leave an older copy alongside the new one. This is neither two-way sync nor an exact folder mirror.
Version history answers a different question
History lets you ask, “What did this file look like earlier?” You need it to undo a bad edit after the edit has reached your current copy. One updated copy mainly answers, “Do I have the file somewhere else?”
Do not assume every sync or backup tool has history. Syncthing, for example, has separate file-versioning settings with specific conditions described in its documentation. Those settings do not make MacSnapshotBackup keep successive versions.
Example: a project on two Macs
You sync a project between two Macs and copy it onto a separate drive. If sync propagates a deletion, the file may remain on that drive because MacSnapshotBackup does not automatically mirror source deletions. But if you save bad contents and a later backup copies them, the previous backed-up contents can be replaced.
Three storage locations are not automatically complete protection. Test a small file through adding, editing, deleting and recovering it. Use disposable test data, never the only copy of an important document.
Plan recovery as well as copying
For frequently edited data, combine a current copy with a method that keeps history. For events affecting your entire workspace, use a further copy in another location. A permanently attached drive is not, by itself, guaranteed protection against ransomware, theft or damage to every connected device.
Sources and further reading
The MacSnapshotBackup description reflects the current product: one updated copy without version history. External tool documentation was reviewed on 27 September 2026.