In some mail I received from John F. Woods, sie wrote
> 
> >> If I recall correctly, on exabyte, EOF markers are "1MB" in size (although
> >> newer tape formats aren't quite so braindead).  So more files on the tape
> >> means less space for real data.  When ypu're backing up in excess of 100,000
> >> files onto the one tape, it makes a difference.
> >That was true of the original 8200 format. Later formats used on the 8500
> >series offered two sizes of tape mark. The long mark, and a short mark
> >which chews up some 128k.
> 
> Of course, neither tar nor cpio stores one disk file per tape "file".  There
> is one EOF mark per tar archive, not per disk file.  If you back up 100,000
> files on one tape, you get one EOF mark.  If you do multiple backups per
> tape, you have one EOF mark per backup, but you're talking tens, not hundred
> thousands, of EOF marks in that case.

Ahh...well, I've been too long in the HP-UX camp...they have an abdomination
called "fbackup", which together with "frecover" claim to some hybrid of
tar/cpio/dump but has got to be the worst thing I've ever had to use (has
the inefficiences I describe above).