I downloaded Mavericks from, the app store and ran the downloaded installer to perform the upgrade. Everything seemed to run normal. Other than confirming what drive to install to, I was never given any other options. After the computer restarted from installing Mavericks, it is behaving like I did a clean install and is asking me if I want to migrate my data from anywhere. Not sure what has happened and am very worried my data has been erased. I have not moved past the screen asking me where I want to migrate data from in case this is savable. EDIT: In Disk Utility when I boot from the installer, it reports the correct amount of space being used on the disk (1.8TB) Thanks for your help!