"...
What is a NetBackup catalog?
NetBackup catalogs are the internal databases that contain information about NetBackup backups and configuration. Backup information includes records of the files that have been backed up and the media on which the files are stored. The catalogs also contain information about the media and the storage devices.
Since NetBackup requires the catalog information to restore backups, configure a catalog backup before using NetBackup for regular client backups. Then, schedule the catalog backups to occur on a regular basis thereafter. Without regular catalog backups, you risk losing regular backups if there is a problem with the disk that contains the catalogs.
..."

and

"...
In order for NetBackup to restore any file, NetBackup needs information from the catalog to determine where the backup for the file is located. Without a catalog, NetBackup cannot restore data.
Because the catalog plays an integral part in a NetBackup environment, a particular type of backup--a catalog backup--protects the catalog. A catalog backup backs up catalog-specific data as well as produces disaster recovery information.
..."

***EDIT ***
This T/N may be of use:
 Listing of Veritas NetBackup (tm) 6.5 and 6.5.x Manuals and links to the respective TechNotes

Catalog backups are a mechanism whereby the internal NetBackup Databases (ie all the data stored to tell NetBackup what data is where on its tapes) and of the NetBackup configurarion. Catalog backups are essential to recover from disk or system disasters and are best kept off site.

Thanks   Dami & AndyWelburn

What  the use of catalog backup, Am new to this technology, can any explain breifly....

then the NBU catalog is very similar to the TSM database.  It is the heart of the application.

Hi rjrumfelt

Can u explain it breif

Look at it this way:

NB is an application that does a lot of things.
All of that configuration you put into NB (policies, schedules, clients, backup list, storage units, tape drives, robots)  is stored on the server in different ways, as well as all the backup image information.
All of this makes the netbackup catalog ( think of it as a big database that makes netbackup run).

Now someone deletes some items by mistake, or you lose your drive that netbackup is installed on, or you lose your whole server, building due to a tornado.

If you want to be able to rebuild your server and restore of tapes you have stored off site without have to read all the tapes back into your new server.... then you use the catalog tape to do a recovery of all that information.

So just like you would backup your Informix, Oracle, SQL database ... so should you backup your NetBackup database using a Catalog backup.

straight forward than Andy's and J.Hinchcliffe's explanations

Yes Mr.J.Hinchcliffe ,   Now i can understand the core things. thanks a lot.

Hi All,If  any body know the installation of client netbckup  on linux machine, If Know just help me with the commanns

you just need to run the install script from the Clients2 CD. that will automatically install the client software.