Sys is correct -- either DDS3 or DDS4 should be able to read these tapes. HP's site has drivers going back to the 12/24 DAT drives, which I believe is DDS3... so if you get an HP drive you're all set for drivers. For greatest chance of suggest, you might want to go with DDS3 over DDS4.
When you say "recover", I worry that there have been unsuccessful attempts to read this data -- is that true, or are we just trying to "read" the tapes, and you don't have the correct tape drive?
You will need the backup application used to write these tapes. If ntbackup, that will be easy; if an older commercial product like BackupExec, it's time to start looking for the software (most commercial packages can read their own tapes going quite a ways back, but make sure you're not surprised). Most commercial packages have a 30-day or 60-day "evaluation license". Since that license is time-limited, I strongly recommend that you not install until you've got a tested, working tape drive in hand, so that you don't use up your eval days waiting for a drive that actually works.
One thing to note: you will in all likelihood be buying a used drive, possibly of unknown condition. I would recommend that your first step with the drive you buy is to run a cleaning tape through it. Second, start with a scratch tape and make sure you can write to and then read the data off that tape. The third step is to take the *least* important of your old tapes and see if it can be read.
MAKE SURE that the write protect tab is set on every tape before you begin, to avoid chance of mistakes.
If you have success in all those steps, then you can start with your restore in earnest. If any one of those steps fails,STOP, and do not proceed until you have analyzed the failure and developed a *plan* to rectify the problem -- preferably having run your proposed solution by at least one other person knowledgeable about tape drives and troubleshooting their problems.
