Security : Backups

Whatever measures are implemented to try and avoid data being deleted or changed, it is impossible to guarantee that this will not happen. Therefore it is vital that extra copies are made of important data. These extra copies are known as backups. For important data a regular backup procedure should be implemented.

Backups should be kept away from the computer room so that they will not be damaged by fires / floods etc. There is no point in keeping a backup if it is likely to get damaged when the original data gets damaged.

The type of backups that are kept usually depend on the type of processing being carried out :

• Batch Processing systems use the Grandfather-Father-Son or Ancestral backup system.
• For Transaction Processing systems a regular backup of the master file is made. As transactions are carried out details of each transaction are stored in a transaction log file. If the master file becomes corrupted the latest backup master file and the transaction log file can be used to recreate it.
• In Real-Time systems there is often little point in keeping backups of data. However much backup hardware is used to reduce the likelihood of the system failing. Sometimes backing up data to disk can be useful in real-time systems. Although this data could not be used to put the system back into its proper state, it could be used to analyse why a system failed. e.g. an aeroplane "black box".

There is a separate article which covers backing up in much more detail.

GCSE ICT Companion 04 - (C) P Meakin 2004