What DeltaSnap cannot do

DeltaSnap restores files. That covers most of what people lose, but it is worth knowing where it stops before you are relying on it in a hurry.

It restores files, not running apps

Mail, Notes, Photos, Messages, and most apps that keep a database do not store your data in one file. They use a main database, a write-ahead log, and side index files that all have to agree with each other.

If you restore one of those files while the app is running, you get a database whose parts no longer match. Depending on the app, it may rebuild quietly, refuse to open, or lose data you still had.

Most of these apps have their own recovery, like a recently-deleted list. Try that first. It knows how to put its own database back together, and DeltaSnap does not.

It does not know about servers

If an app syncs to iCloud, Dropbox, or any other account, your Mac only holds a copy of what that server says. Restore an older copy and the app will sync it back to whatever the server currently thinks is correct.

See Cloud-synced and app data for what to do about it.

It is not a backup

Snapshots live on the same volume as your files. They survive deletion, a bad update, and a script that went wrong. They do not survive a dead drive, an erased volume, a lost laptop, or a fire.

Keep Time Machine or a cloud backup running alongside DeltaSnap. See Safety and backups.

It works one volume at a time

Every snapshot covers a single APFS volume. A snapshot of your startup Data volume says nothing about an external drive, and vice versa. If your work spans both, you need snapshots on both.

It also cannot roll your whole Mac back to an earlier state. It recovers files and folders. For device-wide recovery you need a backup and a supported recovery environment.

It only has what it captured

A version is recoverable while at least one retained snapshot still holds it. If the last snapshot serving that version gets pruned, the version is gone.

DeltaSnap also cannot show you anything from before you installed it. There is no history for a file you deleted last month if your first snapshot was yesterday.

Locations you exclude under Settings → Indexing have no version timeline. The snapshot still contains them, so you can reach them by mounting it or running Compare Everything (Full Scan), but they will not appear in Version Control or search.

Search looks at names, not contents

You can search for a file by its name or path, including files you deleted. DeltaSnap does not search inside files, so you cannot find a document by a phrase it contained.

Very broad searches are trimmed to the best matches rather than returning everything. When that happens the results say so.

A diff tells you what, not who

A comparison reports which paths were added, removed, modified, replaced, or moved. It cannot tell you which app or process made a change, and it is not a semantic diff, so a one-byte change and a rewrite look the same in the list.

The mass-change alarm works the same way. It means an unusual number of files changed quickly. That is worth knowing about, but it is not a malware diagnosis.

Filesystem edge cases

• Hard links restore as independent files, not as links back to the original.
• Symlinks restore as symlinks, pointing wherever they pointed before.
• APFS only. HFS+, exFAT, and network shares have no snapshot support, so DeltaSnap will not list them.
• Restores preserve permissions, ownership, timestamps, extended attributes, and ACLs.

What gets indexed, and what leaves your Mac

DeltaSnap indexes your Library rather than skipping it, because app containers hold sandboxed documents and app databases you cannot recreate. That includes folders you may not think of as documents, such as ~/Library/Keychains and mail storage. The index records paths, sizes, and version signatures. It does not copy file contents anywhere, and it stays on your Mac.

If you would rather a location was left out, add it as a path exclusion under Settings → Indexing.

Three things can leave the app:

• Spotlight. DeltaSnap publishes a list of recently deleted filenames, up to 20,000 per volume, to the Mac's own Spotlight index, so a Spotlight search can offer to open that file's history. This is the on-device index only, nothing is uploaded, and the list is currently not filtered by location, so deleted filenames from Library and app containers can appear in it.
• Network requests. License activation and validation, and update checks. Snapshot contents and your file history are never sent anywhere.
• Email notifications, if you turn them on. Notification text, and with the activity scope the activity log, goes to the mail server you configure and nowhere else. That text can include volume names, snapshot names, and the paths of files you restored or compared. It is off by default; see Notifications and email alerts.

When to use something else

DeltaSnap is the fast layer for everything else: the project folder you deleted, the file an installer overwrote, the work an agent or script mangled, the export that went wrong.