Further, if I take a backup on a piece of media, remove that piece from the backup manager and then replace it, would Netbackup identify it as a fresh piece or a piece with previous backup on it?
Also, how do I calculate how much of the media has been used?
In the second question, if you mean expiring media by "remove that piece from the backup manager", expired backup images can be imported. NetBackup can also import backup images from another server. When images are imported, catalog entries are recreated for those images.
The Media Lists report will provide information on volumes allocated for backups. Among the information reported is the Kbytes column, which indicates the total number of kilobytes of data stored on the volume. It must be noted that, unlike disk space utilization, tape media utilization is difficult to report accurately. This is due to compression used at the device and how well different data types can be compressed. For example, database data can be compressed 4 to 1 in some cases. Therefore, knowing how much data (in kilobytes) is on a tape volume does not necessarily reflect the remaining capacity.
This was first published in April 2005