On Thu, 12 Jun 2003, Jim Sibley wrote: > John, please elucidate. Is the discussion incorrect or did I code the tar > coding example incomplete? If so, what would you have coded?
;-) In one tar command, but not the other, you have specified compression. I think on the S/390 and zeds I'd leave compression off: it takes too long in my brandxBoxes. > > Regards, Jim > Linux S/390-zSeries Support, SEEL, IBM Silicon Valley Labs > t/l 543-4021, 408-463-4021, [EMAIL PROTECTED] > *** Grace Happens *** > > > > > John Summerfield > <[EMAIL PROTECTED] To: [EMAIL PROTECTED] > afe.com.au> cc: > Sent by: Linux on 390 Subject: Re: Linux390 + VM + > Tape 3490 > Port > <[EMAIL PROTECTED] > EDU> > > > 06/12/2003 03:26 PM > Please respond to > Linux on 390 Port > > > > > > > On Thu, 12 Jun 2003, Jim Sibley wrote: > > > >File open-to-close doesn't > > >sound like a very useful paradigm (but I don't know how Linux > applications > > >use tape drives) and I don't know if one part of Linux can open a tape > > >file (tape management system, just to lock the drive and to request a > tape > > >mount) and another part of Linux subsequently > > >opening-writing/reading-closing the same tape so that the drive is not > > >unassigned until the tape management system closes the tape file. > > > > The implementation is what you would expect for a shared printer, a write > > only device - during write, the device is dedicated and after the write, > > the "data" is no longer available. > > > > The assign is done at open/close time, I suspect if one applicaiton > assigns > > the drive and leaves it assigned, then another application uses the > drive, > > then the the assign would be dropped after the second app closes the > file. > > > > As implemented, is dangerous for shared tape, as it does not allow time > for > > operator intervention (loading/unloading the tape) before it is used by > > another hosts, and 2) two hosts could rewind and/or record to the same > tape > > without knowing it. > > > > For example, tar is an applicaiton that can write to the tape directly > and > > read it back. > > > > tar -cvpi -f /dev/ntibm0 > > > > some time later (during this time, another system could do a > > similar function) > > > > tar -xzpi -f /dev/ntibm0 results could be unpredictable or you > > might get someone elses data! > > That will _never_ work, even without another macine stuffing you up!! > > > > > > -- > > > Cheers > John. > > Join the "Linux Support by Small Businesses" list at > http://mail.computerdatasafe.com.au/mailman/listinfo/lssb > -- Cheers John. Join the "Linux Support by Small Businesses" list at http://mail.computerdatasafe.com.au/mailman/listinfo/lssb
