I bought a 1TB 7200 RPM HGST 2.5" Hard Drive for my Macbook Pro Mid-2009. After an install of Yosemite, a number of read/write issues, I sent the thing back for a replacement being told at apple it was likely defective. Again, I did the same, seemed to work fine then the same issues. Eventually, a technician told me that 1TB drive wasn't compatible with the MBP Mid-2009. Does anyone know anything about this? I just bought a 500GB drive by Hitachi, 7200 RPM and am worried it isn't going to work either. So far, I haven't been able to get the computer to recognize the HD, but I'm going to take it to the Mac store to try to install Yosemite and see what they can pull up. Can the MBP mid-2009 run a 7200RPM drive? Is it likely the HD that is broken or do you think there is something broken in the hardware? All these visits have been pretty inconclusive. Thanks.