>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!
I think I'll crank up two hosts on our VM system and see what really
happens under VM.
Regards, Jim
Linux S/390-zSeries Support, SEEL, IBM Silicon Valley Labs
t/l 543-4021, 408-463-4021, [EMAIL PROTECTED]
*** Grace Happens ***
