tar, cmtp, mt, EOF, EOM and multiple tape archives...

tar, cmtp, mt, EOF, EOM and multiple tape archives...

Post by Sean Murphy [ext 33 » Tue, 18 Jul 1995 04:00:00

Could anyone out there in Intel Solaris (5.4) land enlighten me
on this?

With our distribution media for Unix we write and installation script,
1 file, to tape media (1/4", 8mm, 4mm). Afterwhich, the tape is forwarded
past the "EOF" created by the aforementioned tar (mt -t /dev/rmt/1 fsf 1)
and the 2nd tar (release hierarchy) insues.

Now, this works on all 14 Unix platforms we support (and has for 5 years)
until attempting it on Intel Solaris. A variety of differing scenarios
have been attempted w/o success.

The 1st tar archive can't be either written using the "no-rewind" device
or written using the "rewind-on-close" device and then forwarded, but
the results are the same. Doing any operation with the no-rewind device
(be it the BSD 'b' devices or otherwise), the driver never finds the EOF
marker from the tar and goes to the end of physical tape and reports
"End of Media" to the console.

It would appear that the "EOF" marker inserted by the intial tar is "good
enough" to read *that* tar archive with the "rewind" device (the image
is read w/o error and rewinds) but as soon as a forward (or a tar read 'x')
is attempted with the cooresponding "no-rewind" device, the "EOF" for the
1st file is never encountered and the driver (cmtp) goes to EOM.

What gives? Any ideas?