Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!swrinde!cs.utexas.edu!uunet!munnari.oz.au!ariel!duty From: duty@ariel.ucs.unimelb.edu.au (Duty Programmer) Newsgroups: comp.unix.aix Subject: Re: RS/6000 Tape questions Message-ID: <595@ariel.ucs.unimelb.edu.au> Date: 29 Apr 91 23:28:55 GMT References: <1991Apr23.194408.14080@midway.uchicago.edu> <1991Apr24.230308.17971@nmt.edu> <496@nwnexus.WA.COM> Followup-To: rab@tauon.ph.unimelb.edu.au Organization: Information Technology Services, University of Melbourne Lines: 39 In article <496@nwnexus.WA.COM> wjones@nwnexus.WA.COM (Warren Jones) writes: >rmilner@zia.aoc.nrao.edu (Ruth Milner) writes: > >>We have found the Exabyte tape handling (don't have any other kind) to be ... >>unusual ... compared to the Suns. For example, on a Sun, if you write a file >>onto Exabyte, you can take it away and later on put it back in, skip to the >>end of that file, and write another one. On the RS/6000, not only will it not >>do this at all (I/O error), but if you take a tape with a file written on it >>by the IBM over to the Sun, the Sun won't write at the end of it any more >>either! Clearly it's writing something different, but we haven't been able >>to find out what. Anybody have any clues? According to the documentation, >>they both write a double eof on close, and that doesn't really cause us any >>serious problems. > I sympathise. The AIX tape i/o has been driving me crazy for several weeks. However, I think this last problem you mention may be something else. You don't mention whether you can read the IBM tapes on the Sun. If you can't, then it may be that the Sun is using CRC error correction and the IBM is using ECC. You can get the IBM to use CRC by either changing the characteristics of the tape driver (via chdev), or by piping tape writes through 'tctl t write'. Check InfoExplorer for more information. We have had no trouble with 8mm tapes, but the QIC tapes are driving us crazy. Both 'tar' and 'dd' seem to be broken with respect to tape i/o, although it seems that 'tctl' can always read and write tapes. The diagnostic is always 'bad argument', which is rather unhelpful. We have changed the block size from 512 to 0 (variable), and the damn thing still doesn't work. In case IBM is listening, we are running release 3.01.0004.0017 bos.obj. rab --- Richard Brown | E-mail: rab@tauon.ph.unimelb.edu.au School of Physics | Phone : +61 3 344 5081 University of Melbourne | Fax : +61 3 347 4783 Parkville Victoria AUSTRALIA 3052 | Telex : AA35185