SUMMARY: Tape Archive Care...

From: Matt Marlow (matt@gilligan.UCSD.EDU)
Date: Mon Jul 25 1994 - 21:47:47 CDT

Original Message:

Hello All,

It has been suggested in our lab that ALL archive tapes (Exabyte 8mm) be retensioned on a yearly basis in order to prevent damage due to constant magnetic fields. The argument is that, over time, the spooled tape is exposed to a constant magnetic field, caused by its own recorded magnetic pattern, that acts to limit the life of the tape. The proposed solution is to retension the tape - the idea being that it is very unlikely to return to its exact previously spooled position, hence exposing each portion of
 the tape to a new magnetic field.

Has anyone ever heard of this procedure? Is it necessary? Thanks for your help...


Responses were many, but the majority claimed this technique DOES help to
extend the life of spooled magnetic tapes (1/2" reel. 1/4" cartridge, etc.).
A few people claimed they had never experienced difficulty in reading their
archived backup tapes, even though they had been untouched for years. Lucky?
Quite a few people believed they had lost archived data due to this
"imprinting" of various magnetic fields, and a few others felt they lost
data purely because the lifespan of their Exabytes is only a couple of
years! (I'm not sure what the life expectancy is really supposed to be for
Exabytes, but I would assume it is at least a few years! After all, what good
is an archive tape that only lasts 1-2 yrs?)

It was also mentioned that 'mt -f /dev/rstx retension' does not work on
systems running 4.1.3 or Solaris 2.3. It is true! But the work-around
seems to be reading to the end of the recorded data, then rewinding to
the start of tape as follows:

        mt -f /dev/rstx eom
        mt -f /dev/rstx offline

Looks like we'd better start "walking" our tapes every now and then!

There were too many responses to list individuals names, so I would like to
extend my thanks to all those persons who took the time to respond! Hope
this helps...

                                  (. .)
        Name: Marlow, Matthew Michael Nickname: Matt
        Dept: Neurosciences Phone: 534-5560
        Office: 3047 BSB Postal address: 0608
        E-Mail: mmarlow@UCSD.EDU

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