This might not be a real solution, as it still makes use of TAR.
but you could try to use 'file-roller' .
type file-roller in the shell. In my Redhat 9 distro it was included in /usr/bin/file-roller.
it is an Graphical frontend to TAR with the option to use bzip2 or gnu-zip (gz)
TAR in itself doesn't use compression ! so, if you backup 1.8 Gig, the output will also be 1.8 Gig ! Maybe you have run out of diskspace somewhere.
The reason for TAR in itself is uncompressed is:
when you backup files on a tapestreamer and part of the tape has become unreadable then you can still save files from parts of the tar that is still readable.
But since most of the backups today are on harddisk, you could compress the tar with bzip2 or gz.
the program file-roller first creates a TAR file and then automatically compresses it with bzip or gz. (its up to you on which compression you would like to use)
There is also RAR for linux, but is not free.
greetings and regards,