TAPE Backup - All you ever wanted to know...

How do I perform a backup?

    cd /wherever/your/files/are
    tar cvf /dev/whatever .

c	Create the archive
v	Verbose (can be omitted); shows each file archived.
f	File: argument that follows (`/dev/whatever`) is the destination for the archive.
. (dot)	Starting point for files to go in the archive; recursive through sub-directories.

On Linux, tar is GNU tar.
Elsewhere, /opt/local/gnu/bin/tar or perhaps /opt/local/bin/gtar.
Automatic gzip compression with the z qualifier, e.g., tar zcvf /dev/nst0 .

Use NFS (simplest): log on to system that has the tape drive, then access the area you want backed up, e.g.
cd /net/orangutan/export/orangutan_1/
If unsure, cd /net/your-machine-name and see what partitions are exported from your machine.
Use remote or secure shell commands, tar, and dd from your local machine:
tar zcBbvf 20 - . | ssh vagabond 'dd of=/dev/rmt/0ln bs=20b'
GNU tar allegedly has remote tape access ability; untested.