SUMMARY: tar problem, mt problem

From: Clemens Schmuck <clemens_at_wst.edvz.sbg.ac.at>
Date: Tue, 26 Jan 1999 15:48:41 +0100 (MET)

wow, that was fast. in minutes i recived 4 answers which helped me a lot.
thank you very much!!

my first question was:
>tar problem
>===========
>i just encountered a problem with the tar command.
>on my du4.0d i made a cold backup of an oracle database. when resoring the
>data from tape i noticed that the suid and sgid were not stored to tape
>and after the recovery i had to set them by hand again.
>
>the online docu does not tell anything about suid or sgid bits.
>
>my questions are:
>1. is that a festure or a bur - is there a workaround
>2. which other tools do have this feature/bug (cpio, dump, ...)
>3. which tool for backing up oracle dbs do you prefer.

and here the answer:
  tar will save permissions to tape if you have the access rights, but you need the -p
  flag to set them on restore.
  [...]
  By the way, the tcopy command is very useful to find out what is on a tape in
  the way of number of savesets etc.
  In general though, it is not a good idea to use tar to backup *filesystems*.
  Individual files yes,
  file systems no. I have no specific Oracle experience though.
  See the paper of Elizabeth Zwicky on torture testing backup programs
  for details of "not a good idea".

  thanks to Burch Seymou and Oisin McGuinness

----------------------------end question 1

my second question was:
>mt problem
>==========
>on du4.0d i tried to make store several tar archives to one tape. to do so
>i made the first tar at the beginning of the tape then i wanted to
>position the tape at the end of written data on tape. although i tried
>several times i could not figure out how that is done and how one can
>navigate through different files on tape
>
>can anybody please explain and/or give an example?

and here the answer:
  As regards the multiple save set issue, the key things are
  a) use the non-rewind tape device
  b) learn about the fsf option to the mt command for restores.
 
  For example, to tar two file systems to tape:
 
  #!/bin/csh
  #
 
  setenv TAPE /dev/nrmt0h
   
  foreach fs ( /mnt1 /mnt2 )
  tar cf $TAPE $fs
  end
   
  To restore the 2nd from tape:
  #!/bin/csh
  setenv TAPE /dev/nrmt0h
  mt fsf 1
  tar xpf

  thanks to Burch Seymour, Gavin Kreuiter, Partin.Kevin, Oisin McGuinness

----------------------------end question 2

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 clemens schmuck - systemadministator
 edv-zentrum universitaet salzburg +43 (0)662 8044 6731
 hellbrunnerstr. 34 clemens_at_wst.edvz.sbg.ac.at
 5020 salzburg, austria http://www.edvz.sbg.ac.at/~clemens
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Received on Tue Jan 26 1999 - 14:54:21 NZDT

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