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So, backup to tape... Story there. I did a backup system on the mainframe to tapes. The first issue was that the machine room operators would 'recycle' the tape

by daly 9y ago

So, backup to tape... Story there. I did a backup system on the mainframe to tapes. The first issue was that the machine room operators would 'recycle' the tapes they dismounted. So while we thought we had backups, the operators just assumed they were 'scratch tapes'. Second, after having solved that problem we found that a tape was giving us hundreds of thousands of duplicate records. When I visited the actual tape drive I could see that the drive found a bad spot on the tape, did 'auto-recovery' to reread the tape, rinse and repeat. The end result was a physically transparent section of tape. I used to carry it around in my wallet to explain that even backups fail.

DrScump 9y ago
Was that before tape catalogs and volume labels? That was well before my time. In the OS/MVS environment I was in in the 80s, the job's JCL would identify a data set and a relative version number (+1 when creating, 0 for current, -1 for its predecessor, etc.), then the tape catalog would look up the volume number, which was written on the tape case itself (and usually correct). If the operator mounted a wrong tape (either wrong dataset or version), the tape would be kicked off and you'd be prompted again ("you dummy humans can't even handle unpacked decimal?!") It was typical that backup copies be made via an additional DD pass.