The 3-2-1 rule is a backup best practice that calls for three copies of your data, on two different types of storage, with one copy offsite or in the cloud. An extended version, 3-2-1-1-0, adds one immutable or offline copy and zero errors in verified restores, to withstand ransomware.
How TecnetOne handles it: TecnetProtect Backup
3-2-1 rule, 3-2-1-1-0, backup strategy