Sync Is Not Backup: What Your Cloud Keeps, for How Long, and What a Real Backup Adds

You delete a folder on your laptop to tidy up, and a minute later it has vanished from your phone and from the cloud too. That is sync doing its job: it keeps every copy the same, mistakes included. The trash and version history give you a grace period — about a month on most free plans — and after that the loss is final in the cloud as well. A backup is a separate copy that your everyday changes do not overwrite, and one you have actually restored from.

What is happening

Sync repeats every change, deletions included. Apple says that deleting a file in iCloud Drive "removes the files from every device that you're signed in to with the same Apple Account". Apple itself separates the two jobs: iCloud keeps data safe by "syncing and backing up". If iCloud Photos is on, your photos are not part of your iCloud backup — they are only synced. A photo deleted on the iPhone then survives only in Recently Deleted.

Damage spreads the same way. A file you overwrite, corrupt or have encrypted by ransomware is uploaded as it is. Microsoft warns that when you restore OneDrive after ransomware you must clean your devices first, "otherwise, your files could get encrypted again". The UK's NCSC notes that ransomware incidents have also hit connected cloud storage holding backups, and the US agency CISA says many ransomware strains look for reachable backups to delete or encrypt them.

The trash and versions buy time, not safety. What the main services keep (checked 27 September 2026):

A deletion you notice next week is a few clicks to undo; one you notice two months later usually is not.

The Windows "backup" for folders is sync. Microsoft says the Windows Backup app "syncs the folders you specify to your OneDrive account". It is not an independent copy.

What counts as a backup. The NCSC's definition for individuals: "a copy of your important data that's stored in a separate safe location".

What to do

• Start from 3-2-1. In the 2012 US-CERT wording: three copies of any important file — the original and two backups — on two different types of media, with one copy offsite. The rule comes from photographer Peter Krogh and has been popular since the late 2000s. In short: the 3-2-1 backup rule.
• Keep one copy out of reach. The NCSC points out that 3-2-1 "does not require any backup location to be offline" and adds its own rule: never have all copies connected at once. Unplug the external drive when the backup is done. Backup vendors extend the rule to 3-2-1-1-0 — one offline or immutable copy and zero errors when you test a restore; it is a vendor term (Veeam), not a standard.
• Prefer history kept by time, not by count. The NCSC's principles for cloud backups ask for versions kept for a period, so a burst of corrupted saves cannot push the good ones out. "Last 25 versions" is weaker than "30 days of versions".
• Use a tool that keeps history. On a Mac, Time Machine keeps hourly backups for 24 hours, daily ones for a month and weekly ones for all previous months, deleting the oldest when the disk fills. On Windows, File History regularly copies your libraries to an external drive or network location.
• Check that photo originals are really on the computer. If Photos on a Mac is set to Optimize Mac Storage, the full-size originals may exist only in iCloud, and Time Machine cannot copy what is not there. Download the originals or export them, then check that a restore works without the cloud.
• Try a restore: an untested backup is not a backup.
• Phone and photos: backing up your phone, what goes in which cloud, sorting phone photos.

When this is not the case

• You deleted something recently. Check the trash or Recently Deleted and the version history first. On iCloud.com, Recover Files shows what was deleted in the last 30 days.
• Sync is still one of your copies. Against a broken, lost or stolen phone it works — the new device gets everything back; it just does not protect you from your own mistakes.
• Paid plans give longer windows. Dropbox Plus can extend version history to a year, team plans up to 10 years; Microsoft 365 subscribers can roll their whole OneDrive back up to 30 days. But it all lives in the same account: if the account is hacked or locked, the history goes with it.
• A cloud backup expires too. If you turn off iCloud Backup on an iPhone, the stored backups are kept for 180 days and then deleted.
• Official advice does count cloud storage as backup. The NCSC lists iCloud, Google Drive and OneDrive for "backing up using cloud storage", and for irreplaceable files suggests "a copy in the cloud and also on removable media". The cloud is useful; its protection just has an end date.

Sources

• Apple — Delete files or recover deleted files in the Files app
• Apple — What does iCloud back up?
• Apple — Back up your Mac with Time Machine
• Apple — Photos on Mac: iCloud Photos and Optimize Mac Storage
• Google Drive — Delete files
• Microsoft — Restore files deleted from OneDrive
• Microsoft — Detect ransomware and recover files with OneDrive
• Microsoft — Back up and restore with Windows Backup
• Dropbox — Recover deleted files and folders
• NCSC (UK) — Always back up your most important data
• NCSC (UK) — Offline backups in an online world, 2019
• NCSC (UK) — Principles for ransomware-resistant cloud backups, 2024
• CISA (US) — #StopRansomware Guide
• US-CERT — Data Backup Options, 2012 (P. Ruggiero, M. A. Heckathorn)

Checked: 27 September 2026