Multiple backups on tape using tar.
 

I am trying to use tar and mt to manage some of my backups to tape. Each month or so I want to remove the previous months Cold backup .tar files to one tape before deleting them. The problem is when I write any new files to the tape it overwrites the previous backed up files. Is there some trick to appending files into an existing backup or to designate seperate backups, with multiple files contained like January_2009.tar that have just the January backup files, and Feb, etc.

Sounds like you need the fsf option to skip past the 1st archive to set the tape to add a 2nd archive.
See post #5 http://www.linuxquestions.org/questi...nd-file-33514/
http://linux.die.net/man/1/mt

(Possibly eod/seod according to manpage.)
I'd get a test tape and just put a couple of small files on to see what works. Try to recover each file file separately. Lastly, post the technique when you've got it; I'm sure we can all learn from it.

Make sure you are using the non-rewinding version of the tape driver. So, if you are using /dev/st0, change that to /dev/nst0. Otherwise, the tape rewinds after it finishes an operation you have asked for. Your next operation then begins at the beginning again. With the non-rewinding version, it won't do that. Use mt status to confirm where you are before an operation.