🚀 go-pugleaf

In article <CDB76z.7Kx@medar.com> jseymour@medar.com (James Seymour) writes:
> My question
>regards something having to do with perminent damage
>(alteration to tape head geometry?) caused by frequent use of
>certain tape types in this drive.  What will work reliably?
>What (if anything) should we avoid?

This warning is/was posted in the packing with 3M tapes.  This
applies to using different lengths of tape in the older drives
with softer heads.  A wear pattern could be established if one
type of tape were used continually that would make it very hard
and often impossible to read other lengths of tape.

This is because the longer tape is thinner, and under tension
would stretch very slightly.  If you stretch a rubber band you
notice it becomes narrower.  The same thing occurs - but very
slightly in tape.    A pattern would wear in the head for this
narrower tape (because it was thinner) that would cause a
thicker/shorter tape to ride on the ridges created by the
thinnter tape.

This is not a problem in newer tape drives with harder heads.
And is not a problem in drives that continually use both types
of tape as the pattern will not be worn in.

If in doubt on your tape heads, check with the manufacturer,
but no current high capacity tape drives have this problem that
I am aware of.

-- 
Bill Vermillion - bill@bilver.uucp  OR  bill@bilver.oau.org

James Seymour (jseymour@medar.com) wrote:
: We've got a new system (based on SCO ODT 3.x) coming in real soon
: that will have an Archive 525mb SCSI QIC tape drive.  Here's what
: I'm wondering: I have heard/read somewhere about problems with
: different tape drives having problems with different "size" tapes.
: All of the systems we presently have in-house have 125 or 150mb
: drives and one has a 250mb drive (Archive and Wangtek drives).
: 
: Now, I don't think that this new drive will be able to *write*
: all formats and I think it will *read* all of 'em.  My question
: regards something having to do with perminent damage
: (alteration to tape head geometry?) caused by frequent use of
: certain tape types in this drive.  What will work reliably?
: What (if anything) should we avoid?
: 
: While I'm at it: I realize this may not be enough to go on, but
: what formats will I be able to read/write with this beast?

Your "new" 525 MB drive will write all the formats that your 150 MB
drive will will write!

	e.g. it will write 	QIC-120 on DC-600A
				QIC-150 on DC-6150  (150 MB)
				QIC-150 on DC-6250  (250 MB)

If you use DC-6150 and DC-6250 tapes you will be able to move tapes
freely between the 2 classes of drive. The only problem you should have
with the high capacity tapes designed to support the QIC-525 data format.

There are two! DC-6320 (320 MB) and DC-6525 (525 MB). Your 150 MB drives
will write them in QIC-150 data format. Those tapes can still be read on
your 525 MB drives however, the drive will automatically detect data
format. The 150 MB drives will, or course, not be able to read tapes
written in QIC-525 format by your new drives.

Tape length is **NOT** an issue on these drives. There is a potential
problem on the old QIC-24 drives which have a softer head alloy.

Tom

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|  Tom Beach    :   Sr. Engineer   :     Mass Storage Technology          |
|  ADP Dealer Services                                                    |
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 -------------------------------------------------------------------------
: Thanks,
: Jim
: 
: -- 
: Jim Seymour				| Medar, Inc.
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: jseymour@medar.com			| Farmington Hills, MI. 48335
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