Jim, you probably already know this, but for those who might read this in the future, that's always been the downside of NDMP backup. The NDMP protocol is a transport protocol to move data from device to device, with no storage format involved. The tapes are written in different formats by each filer vendor; even though NetBackup may be involved in the backup, it does not decide the tape format. Tapes written by a NetApp can't be read by EMC, or Isilon, or Quantum, etc. If your data retention period is short enough, this isn't usually an issue. But when you have to retain data for years, NDMP backups present a unique problem in recovering that data.
I don't believe there is any easy way to access the data on the old tapes. Based on how often you think you will need to access the old data, I would recommend:
- Probably never, only in legal cases - just make it part of your plan to send the tapes off to a data recovery vendor (Kroll Ontrack?) in those few instances that might happen.
- A little more frequently, maybe a few times a year - keep the old filer hardware onsite and available to power up if necessary to access the tapes.
- Frequently enough - create a disk storage unit and allow Netbackup to duplicate the backups from the old tapes to disk, then duplicate them from disk to new tapes on the new filer. (I've never done this, but assume it would work; someone please corect me if wrong.)
