by Russel Dalenbe » Wed, 27 Sep 1995 04:00:00
I have a number of 9-track tapes that I would like to have converted to
a CD-ROM so that I can access the files on my PC running Linux. Does
anyone know where I could find a service that could do this for me? The
tapes are in tar and cpio formats.
Russel Dalenberg
1. Q:Reliable detection of end-of-tape on 9-track tape (HP/UX)
Hi there!
Can anyone recommend a reliable algorithm for spanning data onto multiple
tape volumes? I am working on a program that writes large files (80 Meg+)
to 9 track tapes. The program is being developed on HP/UX v10.2. The
resulting tapes are to be read on IBM mainframes. The problems start
when I run out of tape and need another reel. Here is the algorithm I am
using to process the end-of-tape:
1. when EOT is hit write() fails and errno is set to ENOSPC
2. make the last block 1 record shorter (the program works with
fixed size records blocked by n)
3. try to write() the block again; if ENOSPC then repeat step 2
4. write tapemark(s)
The algorithm becomes slightly more complicated when I need to write IBM
tape labels, but it's not that important. The major problems I have
encountered so far are outlined below:
1. the EOT flag doesn't clear even after the tape is backspaced
far enough to successfully write the last block and tapemarks.
For the sake of experiment I once tried to backspace until it
clears and it took about 20 blocks 10000 bytes each before it
cleared. I check the EOT flag with ioctl(MTIOCTGET) then
GMT_EOT on the generic device status word. Is there a way to
"clear" the EOT flag? (note: I do call ioctl(MTIOCTGET) after
backspacing and before attempting new writes -- if I don't
the write() fails with errno=EIO)
2. because of the way the EOT flag "behaves" I cannot detect the
"real" EOT reliably. For example:
1. write() fails with errno=ENOSPC; the EOT flag is set
2. the last block is made shorter and written to tape
with no problem
3. the attempt to write a tapemark (ioctl(MTIOCTOP),
command=MTWEOF) fails with errno=EIO
Has anyone ever dealt with a similar problem? Please share your
expertise. Any help on the matter will be highly appreciated! Also, if
you can recommend a book that covers UNIX tape device handling in more
detail then the "Advanced Programming In The UNIX Environment" please
do so.
Many thanks in advance,
Serge
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