Breaking down the file types into different groups can make it easier to understand where they need to be.
- OS & App files need to be on the first partition of your primary HD.
- If you can move temp files to your second partition (see below) Each apps have settings (pref or internal) to alter their location (some can't be alterd).
- What you download or create should be on your second partition and/or external HD.
Laptops - Small HD systems, leave as one partition. If you have a larger HD think about setting up a second partition.
Desktops - Best to have at least two partitions on the internal HD (most have larger HD's - 500meg or bigger). Tip: use pref settings or folder aliases to make getting to the second partition automatic.
Partitioned drives makes backing up easier & quicker as you don't need to backup your OS & Apps as frequently as your data so you can focus the backup on one partition.
Everyone should have at least one external to backup your system.
I have three!
First - Small HD which I have a clean install of my OS to boot from and has my diagnostic and maintenance tools (could be a Flash thumb drive). As you can't defrag the partition/Drive you booted from you use this drive to boot from to defrag your files (checking them first for corruption)
Second - My video editing drive, fast big drive to work off of (defraging after each project)
Third - Backup, holds anything I care about or can't replace from CD/DVD.
Burnable CD/DVD's - Not as reliable as a HD (slower to write or read from as well). Still useful to hold music or downloaded stuff. Best to have a few copies just in case.
Flash drives - more reliable than burnable CD/DVDs for long term storage. But! if you over use them (lots of over-writes) they do degrade.