Magnetic tape filesystem

On Mon, Feb 09, 2015 at 10:50:32AM +1000, Tom Sparks wrote: I have a vague memory of hearing about something (one of the Unices maybe? although handling tapes well is WAY out of character for them) that would attempt to use 9-track tapes as block-replaceable media. Which I think meant using the "erase" command to add 3" of nothing after each block so that you had at least some chance of rewriting that block w/o trashing what comes after (this would cause a huge cut in capacity, but maybe I'm misremembering the whole thing). I've never seen this in person though, and I'm a little surprised that it would work (maybe only on certain drives?). And as others have said, that's on top of intentionally block-replaceable tapes like DECtapes (which act like disks), and file systems that accept the tapiness of it all like ANSI or DOS-11 or CAPS-11 or OS-labeled tapes (where you can write a fresh tail onto the tape from anywhere but you'd better have a plan). And almost everybody's got something like BRU or :DUMP or SAVRES or tar which can store/retrieve archives of disk files on tape -- but that's not the same as accessing tape files through the OS's usual disk-file API. John Wilson D Bit