seek on raw magtape

[John Woods, Software]

> Of course, if you wanted to kludge up your Unix kernel, you could
> make the block tape device use large interrecord gaps, and then you
> could even make a file system on tape.  (Did this once work?  It
> does not in 4.[23]BSD.)
> -- 
This works quite well with normal interrecord gaps on both V7_and_2.8 (using
512 bytes per record) and 2.9 (using 1024 bytes per record).  However, it
give new meaning to the word SLOW...

However, you have to mount the tape read-only.  Even with large interrecord
gaps, most tape drives aren't all that careful where they write a block, and
the canonical behavior is for a repeatedly re-written block to slowly creep
forward, eventually eating up all of that large interrecord gap (and the next
block).

DECtapes, on the other hand...


--
John Woods, Charles River Data Systems, Framingham MA, (617) 626-1101
...!decvax!frog!john, ...!mit-eddie!jfw, jfw%mit-ccc at MIT-XX.ARPA

The Pentagon's Polygraphs:  Witchcraft for witchhunts.