> From: acrocker AT lineone DOT net [SMTP:acrocker AT lineone DOT net]
> >The cleaning tape is abrasive and as such it will contribute to the
> >wearing out of the expensive little heads of your expensive little
> >DLT drives. :)
> 
> I'd just like to finally get to the bottom of this kind of statement. I
believe it to be
> popular myth!  I too also believed that excessive cleaning of DLT drives
would
> increase headwear however I've recently been told categorically by an STK
trainer
> that a DLT cleaning tape is simply a standard tape that has not gone
through the
> burnishing process. As such it's a standard tape (same thickness, same
material) > as a data tape only not polished. Since it's movement over the
heads is identical

"Not polished" is why it is abrasive.  What's being polished is the rough
surface of a layer of iron [oxide] particles that stick out past the binder
and lubricants.

> to a data tape it is impossible to consider that it will increase
headwear. I'm not

Sorry, but even different formulations of standard data tape can increase
head wear.  And _they_ are all polished.  ;-)

> saying this is the truth, but it's the version of the truth which I
currently believe :o)

The friction of tape--any tape--moving over heads wears out heads; it's easy
to see on linear-tape heads.  The rougher or harder the surface, the higher
the relative speed or the higher the contact pressure, the greater the wear.
The only way to avoid it is an air gap between the head and the medium; they
call _those_ "disks."  Or drums if you're old enough to remember.  I've been
out of the business since before helical scan caught on, but doubt these
basics have changed.  

My [Sun] product manual says to clean the drive when the light comes on.
Quantum (don't know about STK) tells you that regularly scheduled head
cleaning is not required for DLT tape drives, and they put a clean-me light
and notification logic in the drive when it would be simpler and cheaper to
just tell you to clean them once in a while.  All in all, I'd say
overcleaning might be more than "a popular myth," which is why the interest
in configuring NetBackup to handle tape cleaning more intelligently than
every N hours.
--
Bob Voll   203 840 5091
WordPROse  bvoll AT newsamerica DOT com