Image backup. pros:
- The files are compressed depengin on the method you are working with, you can save space.
- You can backup any amount of data to DVDs using winrar, you can set the file size manually, later the 'parts' can be rejoined easily.
- If someone else looks at the backuped image, he/she can't find out what is in there, you can password protect rar files and make them read-only, so no one can delte them (HDDs) cons:
- You need a software to access your data.
- Slower access due to the decompressing process (really depends on file type).