Two things,

First, what do you mean that you tried to open the logfile but it did not work? Did it create the log file and it was empty, or was the logfile still in use? How did you try to open it and was there any errors?

Also, be sure to test an import with this export. I've seen problems when you do not use the VOLSIZE parameter, you may need it on export and import.

From metalink....

EXPORTING DIRECTLY TO TAPE
--------------------------

Once you have decided that you need to perform the export directly to tape,
you will need to change the syntax of your export statement so that
export knows the name of the tape device and how much data can be written
to that tape device.

There are only 2 parameters that you need to change to do this :

1. FILE - The name of the tape device you are exporting to
e.g. /dev/rmt/0 .

2. VOLSIZE - The amount of data that can be written to one tape.

If the entire export file will fit onto a single tape, then a volsize of
0 (variable length) can be used i.e. exp volsize=0.
If the resultant export file is larger than a single tape, then volsize
needs to be set accordingly e.g. exp volsize=M.
Please note, there is a 4 Gigabyte limit to the volsize parameter.