A hot backup, also called a dynamic backup, is a backup performed on data even though it is actively accessible to users and may currently be in a state of being updated. Hot backups can provide a convenient solution in multi-user systems, because they do not require downtime, as does a conventional cold backup.
Hot backups involve certain risks. If the data is altered while the backup is in progress, the resulting copy may not match the final state of the data. If recovery of the data becomes necessary (for example, following a system crash), the inconsistency must be resolved. The Oracle database preserves the integrity of the data by creating a so-called redo log prior to executing a hot backup and by placing the system in a special hot-backup mode while the data is copied. Performance may be degraded as the backup is taking place. Individual users may notice this as a temporary system or network slowdown.