The weird part is that large file transfers work fine on the Windows side, i.e. I've tried disabling the sudden motion sensor in Terminal and telling it not to spin down drives when it's plugged in. After unmounting, the drive won't show up at all in Disk Utility and the 'SATA' section of System Information just displays an unknown device. iso files, my music library, etc) to the HFS side of the drive, usually after about 5 minutes both of the partitions on the drive will unmount and display a message about not being ejected properly. When I'm doing large file transfers (DVD. The 1TB HDD is split into 2 partitions: an NTFS side for Windows file storage and an HFS+ side for OSX storage. The stock 120GB SSD houses an OSX Mavericks install and a Windows 7 install, done basically via Bootcamp. I recently installed a 1TB HDD in my early 2011 13' MacBook Pro using an MCE Optibay.
