[PLUG] best strategy for backing up small server

[Mithun Shitole]

Hi,
   I have a small ubuntu server running for our development needs as
well as file server. We are now considering to upgrade it with ubuntu
10.04 LTS. We do not have any automatic backup system for now. I want to
add something like RAID 1 for backing up data. Can anyone suggest best
practices? Should I use and extra internal hard disk or external hard
disk? Is is possible to use fallback hard drive of bigger size and use
extra space for other purposes, such as storing non critical data?
Any pointers to good information?

-- 
Mithun