2nd HDD in Early 2011 MacBook Pro ejects during large file transfers, but only in OSX I recently installed a 1TB HDD in my early 2011 13" MacBook Pro using an MCE Optibay. The stock 120GB SSD houses an OSX Mavericks install and a Windows 7 install, done basically via Bootcamp. The 1TB HDD is split into 2 partitions: an NTFS side for Windows file storage and an HFS+ side for OSX storage.

When I'm doing large file transfers (DVD .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. 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. I've tried disabling the sudden motion sensor in Terminal and telling it not to spin down drives when it's plugged in.

The weird part is that large file transfers work fine on the Windows side, i.e. transferring to the NTFS side of HDD from within Windows.

Any thoughts or advice? I'm considering installing Windows to the HDD, giving OSX full reign of the SSD, and putting a FAT32 shared partition on the HDD. I also have a USB to SATA cable I'm thinking of using to test the drive to see if it's maybe the Optibay or ribbon cable's fault.
The answer:

I took the 1TB HGST Travelstar 7K1000 and gave it a firmware downgrade.  HGST emailed me application to set the port to either, Sata I, II, or III.  Reducing it to Sata II solves the problem.

No more dropping.

Has somethgn to do with Apple/intels first venture into the Sata III world back then.  I used the less expensive Opti bay kit.  Not the more expensive Extreme they have created to solve the problem.

Works great and is plenty fast for a seconday drive.