I got a refurbished imac and am trying to reinstall os X; however, when I do one of the drives is not formatted as mac OS extended journaling and the other is locked. When I click on disk utility the enable journaling is grayed out and the format is ExFat and I am unable to partition to select mac os extended journaled because it says couldn't unmount disk. What should I do? Thanks!
Earlier Mac models
Return that "refurbished" Mac to wherever you bought it and get your money back.
Then buy a properly refurbished Mac from one of these vendors:
New, Used and Refurbished Macs - macsales.com
+1 return the thing. Only buy a refurbished Mac directly from Apple, go to Apple.com navigate to the bottom of the page and you will find the refurbished store. If you cannot afford an Apple refurb (almost anyone can as they offer up to 24 months of interest free financing) then buy a used Mac from a trusted reseller such as Macsales.com.
NEVER EVER buy from places like:
Refurbished Mac can't install OS X
