What do you mean with "online"? Do you want to backup to the Cloud (internet service) or do you want to run a software within your browser to backup to another HDD?
Have you looked at CarbonCopyCloner (which is an application to backup to an external HDD) or DropBox (which is an online service to store data)?
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I want to back up my external HD to a software program (eg Carbonite...well that didnt work),
Now you confuse me more.
Carbonite is an online backup system, meaning you backup to some server(s) located somewhere else via the internet.
You can't backup to a software, as a software is local and stored on your Mac, unless you mean, "online backup service similar to Carbonite" with software.
Have you tried the already suggested method via CrashPlan?
Have you tried troubleshooting Carbonite via the Carbonite Support System?
Carbonite offers the backing up of an external HDD: http://www.carbonite.com/en/blog/In...Your-Carbonite-Home-Home-Office-Online-Backup
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