Today i would like to share my experience with Tape cartridges which i had with my Tape Library in which(Tape cartridges) i was trying to remove specific images.....

Experience

I had Veritas Netbackup 6.5+MS windows2003 server and i was expiring specific backup image(s) from Netbackup administration console-->Catalog but when I was trying to use the command "available_media.cmd" i watched that the status still showing its FULL....even I close and open the command prompt so that it can refresh the status and even Netbackup Administration Console as well but i have not got any success...

Actually I wanted to keep some images in tape cartridges because some images were important for me that’s why I was not removing all those backup images from the tape via Veritas Netbackup GUI administration Console

Resolution

Tapes are linear - meaning that they write from the front to the back.
if we look at a tape...

BOT|day1image|day2image|blankspace|EOT

Now the day1image expires on the tape - the assigned date does not change and you have this.
BOT|expiredimage|day2image|blankspace|EOT

If you try to write to this tape again it will ONLY write in the blankspace as tapes are Linear - meaning they can only append (tapes cannot write here and there like a disk can)