Xbox 360 S 250gb hard drive only showing 50gb

I have an Xbox 360 slim with what is supposed to have a 250gb hard drive, but when I go into system and storage it says it only has 50gb total. I tried formatting and clearing the cache, and aside from this problem, the hard drive works normally. Any ideas
what could be causing this?

:)

 

Xbox originals: Fable

The hard drive your using is not an official xbox 360 hard drive. The only official hard drives available for the Xbox 360 S Console are the 250GB and the 320GB. These are the only drives which have the necessary software on them to play xbox originals
like fable.

 

I can't play Grand theft auto: San Andreas

You won't be able to play any original XBOX games with that current hard drive that you have. You will need to purchase an official 250GB hard drive or a 320GB hard drive from an official retailer (Microsoft Store, Amazon retail, Best Buy, Gamestop, etc).
If you purchase something from eBay/Amazon Marketplace re-seller and it's quite cheap and not in official packaging it's likely that it's a knock off. Since Microsoft never released 120GB hard drives with their XBOX 360 S consoles it's not possible that, that
specific console hard drive was ever official.

Official XBOX 360 250GB Hard Drive

Official XBOX 360 320GB Hard Drive