What is the difference between cold backup and hot backup?

Hot backup is also known as dynamic backup. It is performed in near real-time when the systems are up and running, and new data is continuously generated or captured.

In a hot backup, there is a time parameter involved as to when to perform a backup. This can range from seconds to minutes.

Here, the entire data is copied on the secondary location, and hence the relevant changes reflect in the new backup.

Hot backups are a bit resource intensive as there are multiple iterations stored at a time. This allows the user to restore the backup to a required point.

When the user provides a go-ahead, only then the old backup versions are removed.

Cold backup is also known as static backup. Here, the database operations are entirely stopped, and then the backup is performed.

While the backup is in progress, no business operations can be performed. This is mostly accomplished before the beginning of the day or at the end of the day.

Here a single backup version is made. Since no new data is added to this in real-time, the backup is performed swiftly and only once.

Cold backups consume fewer resources but have a limitation. The database cannot be accessed when the backup operation is in progress.

https://www.hitechnectar.com/blogs/hot-backup-vs-cold-backup/

Cold Backup --> backup taken when DB is offline or down

Hot backup --> backup taken when the database is up and running 

 Cold Backup is a physical backup. During a cold backup the database is closed and not available to users. All files of the database are copied. The data files do not change during the copy so the database is in sync upon restore. Used when service level allows for some downtime for backup

Hot Backup is a physical backup. In a hot backup the database remains open and available to users. All files of the database are copied. There may be changes to the database as the copy is made and so log files of changes being made during the backup must be saved too. Upon a restore, the changes in the log files are reapplied to bring the database in sync.