Just to add to what Artie said, the rule of thumb for a Time Machine backup is the Time Machine volume (drive or partition) should be 3 times the size of the drive being backed up.
CAUTION: with both Time Machine and Clone on the same drive you are placing all of your backup eggs in the same basket. If that drive fails you lose both backup sets.
If we knew what it was we were doing, it wouldn't be called research, would it?
