DC300A tape problems

[Al Donaldson]

Is there some reason why Scotch DC300A data cartridges shouldn't work
properly with a standard Sun shoebox?  I recently bought a batch of 300As
and 300XLs at an auction (new, in boxes, plastic wrapped).  The 300XLs
work fine for dumps, tars, etc., but the 300As won't handle dump at all
(forget exactly what error..) and barely handle tar -- it writes ok but
generally bombs out on reads.

When reading tapes created with "tar cf /dev/rst8" I get the following
errors at different locations on the tape:

  sense key(0x8): blank check, error code(0x34): end-of-medium, or
  sense key(0x3): medium error, error code(0x11): hard data error

I doubt if I'm actually running out of tape (end-of-medium) since the
error occurs at different locations and doesn't occur during write.  I'm
having problems with DC300As written both locally and at other sites, but
I have no problems with DC300XLs, Verbatim DL600ECTs, or the Sony (?)
cartridges used for Sun OS distribution.  Incidentally, the difference
between DC300A and DC300XL is "standard length certified" vs " extra
length certified", whatever that means.  And I routinely do a retension
when I read in a tape from outside, or when I get read errors.  But that
doesn't seem to help.

I'm using "tar xf /dev/rst8", which according to the st man page means QIC
24 format instead of QIC 11.  Can anyone tell me what this means in
practical terms?  I've tried to RTFM, but can't find anything about it in
the tar, st, mtio, ar(4), etc. man pages or in the admin manual.  About
all I know about QIC is that its a group of standards for quarter- inch
cartridge tape.

Any help, pointers, etc will be appreciated.  Please respond by mail since
my comp.sys.sun newsfeed has been interrupted somewhere upline.

Al Donaldson