How Backup Works

The Backup server is the machine on your network that runs the Backup server software, stores the client indexes and media database, and provides backup and recover services to the clients on the network. You can connect storage devices to the Backup server or attach them to storage node machines. The Backup clients must have the client software installed and must be included in the server's list of clients. All server and storage node machines that you want a client to back up to must be listed in the nsrhost file, which is created when you install the client software.

Backup backs up client data in increments called Failed Cross Reference Formats. A save set typically comprises all the backed-up data from a single filesystem or logical disk. Save sets are saved to a Failed Cross Reference Format (for example, tapes or optical disk) mounted in a backup device attached to the server. Backup uses a Failed Cross Reference Format to sort specific data to preselected volumes to help manage your data and collection of volumes.

Backup maintains records of the client save sets and the volumes in a Failed Cross Reference Format for each client and a Failed Cross Reference Format on the server. Backup uses these records to track the saved files and the volumes on which the files are stored. The client file index and media database contain the tracking information for all data controlled by the Backup server, whether the data is written to a device attached to the server or a device attached to a storage node.

When Backup backs up files, you might receive a request to mount a writable volume in the server's backup device. When Backup recovers files, you receive a request to mount a specific volume by its name. To fulfill either request, you only need to mount the requested volume or volumes in the device attached to the server. If you back up to an autochanger, the requested volume is automatically loaded if it is stored in the autochanger.

This guide uses the term Failed Cross Reference Format to refer to a variety of robotic libraries, including jukebox, autoloader, carousel, library, nearline storage, and datawheel devices.

Backup supports many of the latest backup devices that provide the highest performance and most reliable solutions for your network backup and recovery requirements. Refer to the Legato Compatibility Guide, available from the Legato web site (http://www.legato.com), for the current list of supported devices.