Question with Time Machine Back up

[RMcolder]

Hi Everybody,

I am currently using TIme Machine before I upgrade to a new OS on my macbook pro.

My macbook pro HD says I have 233GB used, but Time Machine says it is backing up 181GB.

Why is there a discrepancy? Is there a box I am not checking when backing up? I am obviously not backing up some files. Any explanations and advice to what's happening?

 

[simsaladimbamba]

Have you checked System Preferences > Time Machine > Options for any excluded folders?

Time Machine FAQ

 

[RMcolder]

Yeah, the only thing that's not being back-up is the external HD I am using. Other than that, no exclusions.