From: Deacy, Michael (Michael.Deacy@TycoHealthcare.com)
Date: Fri Dec 13 2002 - 15:51:18 EST
Admins:
Further thanks to the following, for replies after the first summary:
Arnold Sutter
alan.nguyen
Selden E Ball
Gideon Wheeler
Chris Ruhnke
Here are their replies:
Arnold Sutter:
Hello Michael,
at one time the consensus was that the SDLT
cleaning tape is meant for cleaning the tape head
that is responsible for reading DLT-Tapes
(DLT7000/DLT8000) in backward-compatibility mode.
Pure SDLT-Environments thus would not need any cleaning
tapes whatsoever. This might be the reason that the
SDLT cleaning tape is an option and not delivered with
the drive by standard.
Note also that you should never put a DLT cleaning tape
in an SDLT Tape-Drive!
Best Regards,
Arnold Sutter, Senior UNIX Consultant
Selden E. Ball, Jr.:
Michael,
for what it's worth....
DLT drives do need to be cleaned when the light comes on.
And immediately: when the light comes on they already are generating
a high rate of tape read/write errors.
And, too often, the cleaning tape has to be used several times in
immediate succession before the light will go out.
I had an opportunity to discuss this with one of the design engineers
at a DECUS symposium many years ago. The drives were originally
designed to never need cleaning. He was horrified at the idea that
regular cleaning would even be considered. The cleaning tapes are
abrasive and file down the read/write heads in the process of
removing the debris that gets deposited on them.
I fear this belief is still held by many at the support center.
So much for the intent of the design :-(
The DLT tape drives that are in our production environment
last about 6 months before they have to be replaced.
We do our best to provide a clean environment for tape storage and use
but it certainly could not be considered a "clean room" environment.
The only times we've had to replace any tapes have been when they've
been dropped onto a hard surface, breaking the internal gears.
Tape leaders coming off have been a problem once in a while,
but the ones in the drive fail more often than those on the tapes.
Most of our production tape usage has moved to (Qualstar) robots using
SONY AIT-3 tapes, which have similar cleaning characteristics. At least
Sony acknowledges that the drives do need cleaning, and the robots
handle that automatically. AIT-3 tape drives also seem to last somewhat
longer than DLT drives.
I hope this puts your mind at ease about the cleaning, at least ;-)
Selden
======
Selden E. Ball, Jr.
Gideon Wheeler:
Hello,
Just some notes on what I have found. If you use media other than SDLT
ie DLT4, DLT3 etc in the drive then you will need to clean the drive.
Using purely SDLT media then the drive may occasionally require
cleaning.
The SDLT has three heads, one for pre SDLT media and a laser based non
contact separate read write heads for SDLT media. what does this third
head do ? well to fit more data on the tape they had to push the
alignment field to the back of the tape surface.
I'm not entirely sure what the purpose of the A.F. is but if it gets
corrupted then that tape (unless its completely degaussed) is useless.
To test that the A.F. is okay slap the tape in another SDLT and wait. It
should take a3 minutes top to load the header and read the alignment
field anything over 8 minutes and that tape is corrupted. (Listen for
constant tape movements backwards and forwards as it tries to locate the
A.F.)
Earlier firmware releases use to occasionally write a duff AF. Ohh humm
Make sure you have the latest and greatest firmware release
Otherwise it may be duff media.....
R.
Gideon
Chris Ruhnke:
I don't know about the SDLT 110/220 drives; but, on the old TZ8x DLT-III
and DLT-IV drives this light was called the "use cleaning tape" indicator.
In point of fact, it would be better to call it a "needs attention" light.
Just because the light came on was no positive indication that the head
needed cleaning. This light would also illuminate if the DLT media was
"bad". The proper way to check these drives was to load another media in
the drive.
If the light went out, the former cartridge was suspect. If the light
stayed on, the drive possibly needed a cleaning tape.
The fact that the light was labeled "use cleaning tape" caused many
excessive cleaning passes because operators who had not RTFM or had the
sitiuation properly explained to them during training would instinctively
throw a cleaning tape in when ever the light came on.
--CHRis
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