Somewhere in your business, someone believes the accounting data is safe because it lives in Dropbox, OneDrive or Google Drive. This article exists because that belief fails on exactly the morning it gets tested.
Sync copies everything. Including the damage.
A sync tool has one job: make the copy in the cloud identical to the copy on your machine, as fast as possible. It does that job brilliantly. Delete a file and the deletion syncs. Overwrite a working file with a broken one and the broken one syncs. Let ransomware encrypt your drive on a Sunday night and by Monday morning the encrypted versions have synced too, replacing the good ones within seconds.
The tool did not fail. It did exactly what it promises. The problem is that a faithful mirror of a disaster is just a second disaster.
What a backup actually is
A backup is a different animal with three properties a sync tool does not have.
Separate. It lives apart from your working environment, so the thing that destroys your server cannot reach it. Stolen hardware, fire, flood, an angry ex-employee with a password: none of them can touch a copy they cannot see.
Versioned. It keeps history. Yesterday's copy, last week's copy, the copy from before the corruption crept in. When you discover on the 25th that something broke on the 3rd, versioning is the difference between a restore and a rebuild.
Isolated. Nothing on your network can write to it. Ransomware can encrypt everything it can reach, which is precisely why your backup must be somewhere it cannot reach.
The three tests
Whatever your current arrangement is, ask three questions. Is the copy separate from the machines it protects? Can I go back to a date, not just to "the latest"? And if everything I own were encrypted tonight, would the backup survive untouched?
A cloud drive fails all three. An external hard drive in the office fails the first and usually the third. A proper offsite backup passes all three, and the good ones add a fourth property nobody talks about: someone is watching them run. Most backups that fail do not fail loudly. They fail silently in March and nobody notices until October.
What to do this week
Find out where your accounting and payroll data actually lives, not where you assume it lives. Restore one file from your current backup and time how long it takes. Then ask the uncomfortable question: if last night's backup had failed, who would have been told this morning?
If the answer is nobody, you do not have a backup. You have a hope.