Why Sync Is Not a Backup
How File Sync Keeps Copies Matching
Sync vs backup is a common point of confusion. File sync is a process that keeps the same files in two or more places up to date. When you change a file in one location, the change is copied to the others. Services that keep a folder matched across a laptop, a phone and a web account work this way, and so do mirrored folders on a server.
Sync is designed for access and collaboration. Its aim is that every copy matches the latest version, which is convenient when you work from several devices. That same goal has a side effect that matters for backups. Keeping older data for the long term is a separate job, covered in backup vs archive.
Why Sync Copies Mistakes as Well as Files
Because sync aims to match copies, it also copies the things you would rather it did not. A deletion on one device is usually applied everywhere. A damaged or overwritten file replaces the good version on every device. Files encrypted by ransomware on a synced computer can be uploaded and then replace the clean copies on the other side.
Some sync services keep a short version history or a recycle bin, which helps. But that history is often limited in time and size. It is designed as a convenience, not as a long-term record. If you notice a problem after the window has passed, the clean version may no longer exist.
A backup works differently. It keeps a copy from a specific point in time, so a change made on Monday does not overwrite the version from Friday. That history is the essential difference between sync and backup. Some backups also cannot be changed or deleted for a set period, which protects against attacks; see immutable backups.
Frequently asked questions
Can a sync service work as a backup?
Only in a limited way. A sync service holds a second copy of your files, but because it mirrors every change, it cannot reliably restore a version from before a deletion or corruption, unless it offers a long and well-documented version history. For backup purposes, use a tool that keeps independent point-in-time copies.
What is the difference between sync and backup?
Sync keeps several copies identical and up to date, so a change appears everywhere. Backup keeps separate copies from earlier points in time, so an older version can be restored. Sync helps you work across devices. Backup helps you recover from loss, mistakes or attacks.