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From: lcleary@THESIS1.HSCH.UTEXAS.EDU (Len Cleary)
Newsgroups: comp.sys.sgi
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Message-ID: <9103011337.aa15523@VGR.BRL.MIL>
Date: 1 Mar 91 18:37:49 GMT
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Subject:  Multiple tar segments on a single tape

This is an old issue, but I am recently aggravated.  I would like to use
the QIC150 drive on a 4D/20 (3.3.1) as an archival medium in addition to
using it for image backups of the hard drive.  It seems like a waste to
me to use a new 150 MB tape for each 20 MB of data archived.  It is 
possible to append additional segments using:
   mt feom
   mt stat
   tar -cvf /dev/nrtape $FILENAME_PATTERN

For a while, this seemed to work OK, but recently this sequence has not
worked, and I have overwritten 3 segments of previously archived data on one
tape and 10 segments on another.  I found out from this group that 
mt stat is required after mt feom, and a call to the HOTLINE confirmed that,
but there was no additional advice that it might be an intermittent
solution. 

Does anyone have a more reliable archiving protocol?  Am I too greedy to
expect full utilization of the media?  Perhaps the answer is to archive
on an Irwin tapedrive on a PC where the software is better at controlling
the drive.

Thanks for any insight.


Len Cleary, Ph.D.                          lcleary@thesis1.hsch.utexas.edu
Dept. of Neurobiology and Anatomy          office: 713-792-5734
Univ. Texas Medical School Houston         fax:    713-792-5795
P.O. Box 20708
Houston, TX 77225