heres some simplification

cpio -ocvB -O <file>	- copies out
cpio -icvdB -I <file>	- copies in
cpio -icvtB -I <file>	- lists files

cpio -pdmv <destdir>	- replicates file hierarchies
(input for i and p is a list of filenames - 
    like that generated by find for e.g )

SO 

find / -depth -print | cpio -ocvB -O/dev/whateverTheEntryIsForYour4mmtape
or 
find / -depth -print | cpio -ocvB > /dev/whateverTheEntryIsForYour4mmtape
for backup

The find generates the list of files 
the cpio options are
	-o - copy out
	-c - use character header 
	-v - verbose - print filename list 
	-B - block io to 5120 bytes/record (10 blocks) if going
		 to a char device
	

(you can probably get away wihout the v and B options ).


restore fm tape with 

cd /
cpio -icvBd -I /dev/whateverTheEntryIsForYour4mmtape
or 
cpio -icvBd < /dev/whateverTheEntryIsForYour4mmtape
    -i - copy in
    -c - Character header
    -B - same blocking
    -d - create directories if needed


look at tape with 
    cpio -icvBt -I /dev/whateverTheEntryIsForYour4mmtape
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