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Writing Good Bits (1Mar94)
(from KPNO, NOAO Newsletter No. 37, 1 March 1994)

The observing support staff has dealt with a number of cases recently
where observers had considerable difficulty in writing their data to
Exabyte tape.  In nearly every case the observer was using "video
grade" tapes rather than computer grade tape.  Switching to computer
grade tape invariably fixed the problem.  This has led to frustration
on the part of the observers, who waste hours dealing with the Exabyte,
and also to wasted effort on the part of the support staff, in
attempting to chase a problem that was due to poor quality tapes.

We therefore remind you that quality really does count - either bring
computer grade tapes with you, or buy the tapes from us on the
mountain.  We buy Sony QG112MAa tapes and have yet to hear of any
problems when observers use them.

We also wish to remind observers that although the "Save the Bits"
archive has been in full-swing operation for several months, the
responsibility for the safety of your data remains your own.  We
strongly urge all of our users to follow the "safe taping" procedures
given in the ICE manual:

1) Each night write your data to tape in FITS format using whatever media
   you like (Exabyte, DAT, nine-track tapes).

2) Read the headers on the tape to make sure all your data is really there.

3) Remove the tape, take it with you when you leave the dome, and stick
   it under your pillow.

4) During your run make a second copy of your data (this may be on a single
   tape containing everything from the run).

5) Only when you have substantiated that the data is also on the second
   tape is it safe to delete images.

Di Harmer, Jim DeVeny, Phil Massey

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