The limitation in a 15inch early 2011 mbp is that the hdd should have a height of 9.5mm and that the SATA port only works reliably with drives that connect at SATA 2 speeds (3G bits/sec)
To use a hdd in the optical drive you have to use an adapter, of course. The height is easy to verify.
I'm looking for the drive with the most storage space that will work reliably in this case.
There are reports that the 1.5TB hdd by HGST works in this case. Are there any other drives that work?