Recovery from Errors
For a system to run efficiently, it has to recover from errors. There are three major ways of doing so: re-input, re-transmission and restoring from backing up.
Re-input: After errors are detected through validation or verification, they can be fixed simply by correcting the invalid data entered. In a batch process, though, the errors will be reported, and the correct data will have to be entered on the next batch.
Re-transmission: When parity checks catch a transmission error, there will usually be a request for re-transmission. However, some errors can be automatically fixed.
Backing up: When organizations rely on computer-stored data (large companies, banks, government branches, etc…), their systems are thoroughly protected. They create daily backups for each action of the day. Typically, the backups are well protected (fireproof case, and other such measures) and kept in a different location than the data for security reasons, since that information is key to running the business. There are two types of backups. Full backups save a new copy of every file in the system. Incremental backups save only new files or others that have been modified. Most commonly, backups are stored in tape, due to the medium’s cheap price and large storage capabilities.