Determining database backup needs for your site

Reasons for database backups

A backup protects against unexpected media failure or corruption of the database. If you experience media failure, you can recover the most recent database backup.

CAUTION! Failure to create a database backup may result in the loss of critical data.

If the database is not backed up regularly, the disk where the transaction logs are being stored may run out of space, causing the database to hang.

If the structure of the database ever changes, perform a database backup immediately afterward.

Frequency of database backups

The database can be backed up while it is open and being used.

Back up the database at the end of every working day. Therefore, if the database is being used only Monday to Friday, back up the database five times a week. If the database is being used Sunday to Saturday, back up the database every day of the week.

Database backup media

On SQL Server databases, to perform database backups, you need a tape drive that is supported by SQL Server. Consult the Microsoft documentation for a list of supported tape drives.

When backing up to tape, use a standard backup strategy. For instance, for a one-week backup, a minimum of seven tapes would normally be required, one for each day of the week. A one-month backup can be built using a minimum of 10 tapes. Multiple copies of the daily tape backups are recommended to guard against the unintended use of defective tapes. No matter how many tapes are used during a backup cycle, keep all the incremental tapes, between the oldest and the most current, as well as at least the last full backup, so that all necessary transactions logs can be replayed after the last restore is completed.

Only disk backups are supported for Oracle for Windows databases. If required, site-specific third-party add-on backup tools can be used to extend these disk backups to tape and/or enterprise mechanisms already in use at the site.

To perform backups to disk, you should allocate enough disk space to store a minimum of three days of database backups.

To determine the amount of space required for disk backups, an Excel spreadsheet called the Database Configurator tool can be used to determine the size of various Oracle database partitions, based on estimated or initial exam volume and anticipated growth for the next five years.

The Database Configurator tool is available on Mednet at the following location: http://ftp.agfa.be/HE/software/PACS/3rd_Party_Solutions/Oracle/Software/database_configurator/.