A small backup checklist
A backup is only useful if it can be restored. These five questions are worth answering for every system you look after.
1. Is there more than one copy?
The classic rule is three copies, on two kinds of storage, with one copy somewhere else. It is old, and it still holds up.
2. Is it separate from the thing it protects?
A snapshot stored on the same disk, or reachable with the same credentials, disappears together with the original in the cases that matter most.
3. Is it encrypted?
Backups often hold everything, including secrets. Encrypt them and keep the key somewhere that is not the backup itself.
4. Have you restored from it?
Schedule a restore test, even a small one. The first restore should never happen during an incident.
5. Will you know when it fails?
Alert on missing or unusually small backups, not only on error messages.