🚀 go-pugleaf

I am having an interesting problem with an Exabyte-8500.  My dump
happen automatically every night.  The tape format has a 30MB blank
file at the beginning of each tape followed by the dump structures.
After the dumps have finished, I generate an index by getting a
directory listing of each dump structure.  I then write this index on
the beginning of the tape (with a few other files) in the 30MB blank
file.  I have used this on 8200's for two years with no problem.  I
use a modified tar for the index write which rewinds the tape before
closing which keeps the device driver from writing a second EOF.

This approach does not work on the 8500's.  I write a 30MB blank file,
do the dumps without error and use the modified tar (or any other
utility I have tried - regular tar, dd) and once the index is written,
I cannot mt fsf over that file - get an IO error.  Does anyone have a
good reason for this?
--
Kevin M. DeFord
Internet: deford@linus.mitre.org; UUCP: {decvax,philabs}!linus!deford
Office: 1A423, phone (617)271-3424
Mitre Corporation, Bedford, MA 01730