hyman@ria.ccs.uwo.ca (Hyman Wong) (06/06/91)
Hello out there in UNIX-land! I need some assistance in the usage of
tapes. Specifically, I'm trying to do dumps of disks to a tape, except
I want to use the tape for more than one dump. I'm trying to keep an
index of all the files dumped so far as the first file on tape, which
will be used for restoring any files. The index is pre-allocated on the
tape to about 1mb. When I go to use the tape again for another backup,
I read in the index, position the tape to the last record, and dump
files, adding the filenames and other useful info to the index. Then
when the dump is done, I rewind the tape and rewrite the index to the
allocated space at the beginning of the tape.
Now here's the problem, after rewinding the tape and writing out the
index, I get two End-Of-Tape markers after it, to signal the end of the
tape. Here's what it looks like:
file 1, EOT, EOT, file 2, EOT, file 3, EOT, EOT
~~~~~~~~Yikes!
The problem is that I can't seem to read past the first pair of EOT
markers, no matter what I try. Is there a way of doing it with mt, dd,
or tar? Anyone know of a another way to read past the End-Of-Tape
marker pairs?
Any suggestions, comments or advice is greatly appreciated.
-------------
Hyman Wong (hyman@ria.ccs.uwo.ca)
Computing and Communications Services
The University of Western Ontarioals@bohra.cpg.oz.au (Anthony Shipman) (06/06/91)
In article <3282@ria.ccs.uwo.ca>, hyman@ria.ccs.uwo.ca (Hyman Wong) writes: > Hello out there in UNIX-land! I need some assistance in the usage of > tapes. Specifically, I'm trying to do dumps of disks to a tape, except > I want to use the tape for more than one dump. I'm trying to keep an > index of all the files dumped so far as the first file on tape, which > will be used for restoring any files. The index is pre-allocated on the > tape to about 1mb. When I go to use the tape again for another backup, > I read in the index, position the tape to the last record, and dump > files, adding the filenames and other useful info to the index. Then > when the dump is done, I rewind the tape and rewrite the index to the > allocated space at the beginning of the tape. > > Now here's the problem, after rewinding the tape and writing out the > index, I get two End-Of-Tape markers after it, to signal the end of the > tape. Here's what it looks like: > > file 1, EOT, EOT, file 2, EOT, file 3, EOT, EOT > ~~~~~~~~Yikes! > > The problem is that I can't seem to read past the first pair of EOT > markers, no matter what I try. Is there a way of doing it with mt, dd, > or tar? Anyone know of a another way to read past the End-Of-Tape > marker pairs? > > Any suggestions, comments or advice is greatly appreciated. > With traditional 9 track tape systems a skip to the logical end of tape would leave you between the two EOTs. Then a skip file or skip record could skip to file 2. It depends on what the driver will let you do. -- Anthony Shipman "You've got to be taught before it's too late, Computer Power Group Before you are six or seven or eight, 19 Cato St., East Hawthorn, To hate all the people your relatives hate, Melbourne, Australia You've got to be carefully taught." R&H
edw@sequent.UUCP (Ed Wright) (06/08/91)
In article <3282@ria.ccs.uwo.ca> hyman@ria.ccs.uwo.ca (Hyman Wong) writes:
%Hello out there in UNIX-land! I need some assistance in the usage of
%tapes. Specifically, I'm trying to do dumps of disks to a tape, except
%I want to use the tape for more than one dump. I'm trying to keep an
man mt
man mtio
--
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ZZZZ ^H ^@ ^L ^[c ^# ^E ^X ^I ^T ? help helpquit ^D ^d ^C ^c help
^]q exit ?Quit ?q anybackbone!sequent!edw edw@sequent.COM KA9AHQ 28.340