Usually, Bank A will test the disaster tolerance during the emergency drill of the business settlement system. Then "disaster tolerance" is ().

Disaster recovery system refers to the establishment of two or more sets of IT systems with the same functions in remote places, which can monitor health status and switch functions between them. When a system stops working due to an accident (such as fire and earthquake), the whole application system can be switched to another place, so that the system functions can continue to work normally.