Chosen Solution
I have a 2011 Macbook into which I have put a SSD in the main hard drive buss and moved the old hard drive to a housing in the optical drive bay. It has worked fine for the better part of three years. Today the computer crashed (I think I had run out of disc space… it had been a while since a reboot and I notice that the drive starts having less and less space available as time goes on - I am guessing some temporary files that never get deleted or something). When I restarted it wouldn’t boot. (I have once or twice before had the SSD not be recognised on reboot, but a subsequent reboot always set it right). So in my trouble shooting, to test the SSD (due to lack of an external casing for test purposes) I switched the drives so that the SSD was in the optical bay and the old HD was in its original spot. Low and behold, it booted up. I trashed a bunch of recovered files that were in the trash (not unusual, I have always got some recovered files in reboot since installing the SSD). I made some space, backed up. And thought: Happy days! I switched them back over - NEITHER was recognised (The HD is also a bootable disc, at least it was)!!!! So I switched back to the SSD in the optical bay and the HD on the original buss and bam! It works all again. All this makes no sense to me… Does anyone have any idea what might be happening??? It works as is, but I would prefer to have the SSD with OS X on it in the HD bay as i believe the buss speed is greater there than the optical bay.
Heres the full run down on the why and how to prevent future damage: Why are hdd cables failing? And here is the IFIXIT guide you’ll need to follow to replace the HD cable: MacBook Pro 13" Unibody Early 2011 Hard Drive Cable Replacement and here’s the needed cable: MacBook Pro 13" Unibody (Mid 2012) Hard Drive Cable But! Before you tackle this why don’t you try getting Apple to fix it for free! They have been quietly replacing the cable.
