What Is a Backup?
A database backup is simply a representative copy of data. When the original data is lost, you can use the backup to reconstruct lost information (that is, the physical files that constitute your JADE database). This copy includes important parts of your database such as the control file, transaction journals, and data files.
In the event of a catastrophic failure, your database backup is the key to successfully recovering your data. (For details, see "Types of Failure", later in this chapter.) Additionally, restoring and recovering a database from a backup can be operationally useful; for example, when moving or copying a database from one server to another.
By backing up a database from one computer and restoring and recovering the database from the backup to another computer, a copy of a database can be made quickly and easily.
As backing up and restoring a large database is a lengthy process, and backups of very large databases become impractical to perform on a regular basis for systems with high availability requirements, the Synchronized Database Service (SDS) provides an alternative recovery strategy. For details about using an SDS environment to keep secondary copies of a database synchronized with a primary updating copy and to provide read-only access to secondary copies of the database (for example, for the design and deployment of high workloads), see "
