CLEANING AND RECERTIFYING
MAGNETIC TAPE
How important is tape cleaning and recertification?
Let us answer that question by asking another question:
When do you suppose tape failures are most likely to
occur? If you answered, when the tape is being used on
the computer system; then you are correct. Consider this
example: an unrecoverable tape error appears while the
operator is trying to read in reel four of an eight-reel
master file; the operator is about 3 hours into a very
important job, and finds out there is no way to recover
(restart) the job starting with reel three of the input. A
failure at this stage of the operation gets the operator
and a good many other people very upset, for we all
know that reruns are costly in both time and money.
Such failures can be avoided if tapes are cleaned and
recertified on a regular basis. It is well worth the effort
to properly care for tapes according to a regular planned
schedule; since this avoids upset and inconvenience and
gives your users confidence that your AIS facility is
running smoothly.
Careful and planned maintenance of magnetic tapes
can minimize and even possibly eliminate a lot of lost
computer time. The first step in every magnetic tape
maintenance program is, obviously, careful cleaning.
Despite the many safeguards against contamination, you
can believe that magnetic tape will eventually acquire
some contamination and cause read or write errors.
You will find the greatest number of tape errors
normally occur in the first 100 feet of a reel. When this
is the case, the appropriate action is to cut off the
contaminated area, relocate the BOT reflective marker,
and continue to use the tape (see figure 2-11). In most
cases, the reduced length will not detract from its
usefulness.
This procedure is known as stripping a tape. After a
tape has been stripped five times, it should be reloaded
(transferred) onto what we call a mini-reel. A mini-reel
is about half the size of a standard reel of tape.
If the errors continue throughout the length of the
tape, you should determine whether the errors are
distortion errors or dirt errors. Distortion errors are
usually the result of careless handling (abuse) of the
tape and can rarely be corrected. Distortion errors can be
seen as wrinkles, creases, turned-up edges, or a slight
stretching of the tape. Dirt errors usually result from the
accumulation of microscopic foreign matter on the tape
surface and can be removed by careful cleaning. To do
this, you need to use a tape cleaner.
Tape cleaning is the process of removing all
foreign particles (known as residual buildup) and
protruding debris from the oxide and back side (the
shiny side) of the tape. This process does not destroy
any of the data that has been previously recorded on the
tape.
New tape has a tendency to shed oxide particles
near the surface for approximately the first six passes
through the read/write heads of the magnetic tape unit.
Unless the new tape is cleaned at least twice, increased
tape unit head wear could result. You will also find that
deterioration of the edges of the tape is the major cause
of most tape-generated debris. Edge guides that help to
direct the tape along the tape path also cause a constant
edge-scuffing. This results in a further breakdown of the
oxide/base layer interface of the tape. An effective
Figure 2-11.—A 100 feet of contaminated tape being removed from reel (stripping).
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