These are the actual files that make up the backup image. They are just tar files but the latest version of netbackup tar, which is nbtar has been changed and to the best of my knowledge, cannot be used manually to undo tar files.
Previously, when we just had /usr/openv/netbackup/bin/tar it was possible to manually read backup images (at least from tape) but as mentioned the functionality has changed.
Feel free to try, I could be wrong as I've not tried it recently - but copy the files somewhere else first. I'll be blunt, playing around with these files risks data loss, and is completly unsupported.
