Difference between Online(hot)and Offline(cold) backup
Offline backup(cold backup)is a database backup performed when the database is disconnected from the network(not accessible while updating,because it avoids the risk of copying data that may be in the process of being updated). It required downtime.
Online backup(hot backup or dynamic) is a method of offsite data storage in which files, folders, or the entire contents of a hard drive are regularly backed up on a remote server or computer with a network connection.
computers are connected to the Internet, automatically copying selected files to backup storage sometimes called Web-based backup.