Dima P. wrote: It’s done to ensure that all drives can restore tape written within one library. However, maximum/minimum value is retuned by the library/drive itself.
Hmm, that's actually not always relevant, & may well be a contributor to my issue.
The reason is, in my "problematic" environment, I have two libraries - one has an LTO-6 drive in it, the other has an LTO-6 and an LTO-4 drive in it. (Primary reason was we used Backup exec & sent full backups to LTO-6 tapes (3+TB at that time) and daily incrementals <100Gb each went to LTO-4 tapes to save on costs as there was no sense in writing <100Gb files to 2.4Tb tapes & send them off daily.
The LTO-6 drives will happily restore an LTO-4 tape, but an LTO-4 drive can't do a single thing with anything higher than an LTO-4 tape.