Released June 2012, Model A1278. Intel processor with Turbo Boost, Up to 512 MB DDR5 Video RAM

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OptiBay SSD has issues handling files


I recently installed a Samsung 840 EVO 250GB SSD in a HDD caddy after removing the internal dvd drive. The SSD was working fine in the normal HDD slot before. but I'm having issues with it inside the caddy now.

OS-X recognizes the SSD and the HD diagnosis tool confirms it appears to be OK on check although it did NOT for the first few trys of checking/repairing.

Block Image

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I can format the drive just fine using the HDD tool inside OS X. I can copy files to the SSD. I can rename files on the SSD. Now the issues:

  • Files copied to the ssd appear to be broken and can't be opened (example with a few images below)

Block Image

  • I originally intended to use this drive for BootCamp with Windows 7. When I try to install windows 7 the installer says that Windows can't be installed on the selected drive (the optibay SSD)

Additional hardware specs:

  • MacBookPro9,2
  • 16GB crucial Ram
  • Primary SSD inside main HDD slot: Samsung 850 EVO 500GB
  • Secondary SSD inside optibay caddy: Samsung 840 EVO 250GB
  • CPU: 2,5 GHz Intel Core i5 (Intel HD4000)
  • Boot-ROM-Version: MBP91.00D3.B0B
  • SMC-Version (System): 2.2f44

I hope any of you guys can help me out. I don't think this is a hardware issue as the SSD is recognized fine and also because I was using it as primary in the main HDD slot literally a day before I changed the setup.

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1 Answer

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First you should double check your systems firmware. Here's the Apple T/N on how to check and update: About EFI and SMC firmware updates for Intel-based Mac computers. While this is not your main issue it does effect you when running Windows.

The main issue you are facing here is a known issue with the Intel Platform Controller Hub chip this series of systems use. The secondary SATA port (Optical drive) is not SATA III (6.0 Gb/s) but something slightly in-between SATA II (3.0 Gb/s) and SATA III. This is a result of the clocking the chip uses. You will need to install a fixed SATA II drive in the optical drive carrier. It makes no difference who's carrier you use as the carrier is just a signal passthrough device. Here's OWC Data Doubler info page on their unit. Scroll down to the bottom of the page and just under the Red note you will see this:

MacBook Pro 13" models: Apple does not support the use of 6Gb/s drives in the optical bay. While we have observed a high rate of success using SATA 3.0 6Gb/s drives in Apple 13" bays where 6Gb/s link is present, some systems may not operate properly with this setup. For guaranteed reliability/compatibility, we suggest 6Gb/s drives be used in the main drive bay only, and 3Gb/s hard drives or SSDs be used in the optical bay when a two-drive configuration is desired. We cannot guarantee proper or successful 6Gb/s drive operation in the Apple MacBook Pro 13" optical bay.

OK, So I can't use the SSD in the optical drive then can I put it back into the HD's location and then move the HD over to the optical carrier? NOPE!

Sadly, you have two issues: Apples HD drive is SATA III so it too will encounter issues (file corruption) if used in the carrier just like the SSD. The second issue here it only the HD SATA port has CrashGuard to protect the drive from bumps. This is a sensor on the logic board as well as the rubber mounts for the drive. Some 3rd party HD drives have onboard drive protection which you will want if you still want the HD in the carrier.

OK, what to do here trying to install a SSD drive? Your options are a bit limited here:

Finding a fixed SATA II SSD is almost imposable now as all being made with auto SATA speed sense technology which won't work here as the SATA port is 1/2 between SATA II & SATA III (which is why it works sometimes).

The other option is to go with a larger SSD so you don't need the HD for the deep storage (big bucks $$$).

The next option here is to go with a SSHD which is a HD with a deep SSD cache. Seagate makes a nice one Seagate Laptop SSHD. We have fitted over 200 MacBook Pro's with them to gain performance. While it is not a SSD it gets you quite far.

The last option here is going with a dual drive that only needs the single SATA port (HD port). Western Digital offers a Black2 drive which is exactly that! It allows you to setup either as a Fusion Drive set or as discreet drives. I've played around with one for a while and it works quite well. We had already locked in on the Seagate solution before WD offered Mac support with their drive. We might have gone that way if the drive handled the bumps our field guys give the systems.

So the bottom line here is forget the optical drive setup unless you get a fixed speed SATA II drive (HD or SSD). Instead go with either the Seagate SSHD or the Western Digital Black2 drive.

Update: Western Digital has withdrawn the Black2. Your only solution now is the Seagate SSHD or the released WD SSHD (which is a fixed SATA III drive).


Your Windows 7 issue is related to how BootCamp works. You need to setup the SSD as your boot drive and run BootCamp (and Windows) within it. But until you fix your drive issues you'll need to wait to get this working.

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Thank you very much for your reply Dan! That's disappointing news. :-/


Sorry it didn't work out as you had hoped ;-{


Hi, Dan. I found this thread in the Answers Forum and wanted to ask about some proposed changes I have planned for my MacBook Pro, which is identical to cityy's (except I currently still have the 500 gb hard drive that shipped with the laptop that is not an SSD) . I ordered the Samsung 850 EVO 250 GB to place in the Optical Bay of my laptop. If I understand correctly from this thread, it will not work reliably unless I use it in the normal HDD slot. Is this true? If I put the SSD in the original HDD slot, will the existing HD that shipped with my machine work in the Optibay?

I feel that the site's Dual Drive guide for this specific MacBook (Installing MacBook Pro 13" Unibody Mid 2012 Dual Hard Drive) is misleading since the recommended parts include SATA III drives that apparently won't work in the secondary SATA port.


@ leftfield78 - Sorry guy same issues here! Stick with the SSD drive (you may want a larger one) in the primary drive location (HD) and call it a day. Don't move the HD to the optical carrier it just won't hold up for very long. Or, go with a SSHD drive like Seagate for your primary drive. Which is what I strongly recommend if you need a cheaper solution than a 1TB SSD. I don't recommend dual drive setups in MacBook Pro unibody systems.


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