I believe cpio is an older program than tar. You may want to look in the tar info manual in section 5.2 which deals with incremental dumps and restores. It uses an option to produce snapshot files that are used to determine which files need to be backed up. Another option with tar or cpio is to use a find command to locate files newer that a certain date or newer than a particular file.
If you are going to use tar for backup, I'd recommend installing the tar source tarball. After the "./configure" stage, run "make pdf" or "make dvi" to produce a printable manual. You don't need to run "make && make install" since it is already installed.
Be sure to read up on whether file attributes, acls and security attributes are backed up as well.
There is a version called star that backs up security attributes as well, but a newer version of tar might with the correct options.
A backup program I like is dar which stands for Disk ARchive. It creates slices that you can burn to CDs or DVDs. It has a nice front end called "kdar". You can set up your jobs in kdar, and from kdar export a bash script that uses dar without a graphical front end. So you can use a handy gui for setting up you backups but have a cron job to perform the backups.
note: section 8.4 of the tar manual compares tar and cpio.
Last edited by jschiwal; 06-08-2008 at 03:45 PM.