Jobs failing with Error 84: Media Write Error.

Don't jump to conclusions that the tape is bad, or that the drive is bad, or that something else isn't in play. The issue is with writing. First off you want to get a bptm log, a bpcd log, and a bpbkar log if you can to see if theres anything unusual popping up around the <16> and <32> error codes.

Steps:
1. See if the drive is bad first, down the drive and force that tape to be used in a different drive from that same media server.
2. If step 1 succeeds, congrats, you need to inspect that drive. If not, try a different tape on a different drive on that same media server.
3. If step 2 succeeds, congrats, its potentially that tape. If not, try a different client on the original tape from that same media server.
4. If step 3 succeeds, congrats, its potentially the client writing something it doesn't like. That unfortunately takes more logging. If not, try a different client on the different tape on that same media server.
5. Same as above, except now multiple potential issues. Next, if it doesnt work, try the original stuff on a different media server.

Really its eliminating the possible issues. Everything from an hba, to disk, to type of backup, to client version, to tapes, to cleaning scenarios, to network blips can mess with a media write.