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

1083 Questions View all

Dual Harddrives - Reliability issues? / HDD size limit?

Hi there!

I've been scouring Youtube / Google / iFixit for guides on how to run two harddrives at once for my Macbook Pro.

My plan is to:

- Use a 250GB SSD in the primary harddrive slot

- Use my existing 1TB HDD in place of the optical drive slot

However, I've noticed on the iFixit kit, that there is a limit of 750GB for the optical drive slot. Why is that?

Also another question, for anyone who's had the dual harddrive setup for an extended period of time, how has it been holding up? ex) has there been any crashes? Any harddrive failures?

Thank you in advance,

Answered! View the answer I have this problem too

Is this a good question?

Score 0
Add a comment
Spread Fixmas Cheer
Get $12 off your purchase of $50 or more with code FIXMAS12
Spread Fixmas Cheer
Get $12 off your purchase of $50 or more with code FIXMAS12

1 Answer

Chosen Solution

I would first recommend you review this: OWC Data Doubler note the Red text at the bottom. It makes no difference who's optical drive carrier you use if you have the system that has an issue with the optical drives SATA port.

As to where to place your SSD I would recommend it put it in the optical drive carrier as your systems HD crash guard protection is only located in the HD bay so moving the drive over to the optical carrier will put it at risk for damage if you bang the system while the system is running.

As to the size the carrier can support the limit is the height of the drive (Z). The limit is 9.5 mm. The note is a bit dated as many of the 1 TB drives were higher. If you review the spec sheet of the drive you are looking at you want to make sure its not too high no matter which bay you put it in. Both are limited to 9.5 mm.

So to review things here:

  • Leave the HD drive in its current location otherwise your drive could fail
  • If you upgrade it it still needs to be no higher than 9.5 mm
  • Adding a SSD in place of the optical drive maybe tricky! Depending on your exact model review the OWC note.
  • If the best you can put in is a SATA II (3.0 Gb/s) drive make sure you get a fixed SATA II drive, don't get an auto sense drive (one that can run in either SATA II or SATA III systems) as it won't work either.

Personally, I would recommend you go with a SSHD like the Seagate Laptop SSHD as your HD replacement and leave the optical drive alone. That way you get the bang of the deeper SSD cache in the drive and yet have the larger traditional storage it offers. Here's the IFIXIT kit: 1 TB SSD Hybrid 2.5" Hard Drive - Upgrade Kit which has everything you need.

1 TB SSD Hybrid 2.5" Hard Drive Image


1 TB SSD Hybrid 2.5" Hard Drive


Was this answer helpful?

Score 2


Thanks for the fast response and for all the information!

I'll be keeping the HDD in it's original spot. As for your recommendation, the only reason why I lean toward the SSD, is because it offers faster speeds than the hybrid drive. However, I'll definitely keep the SSHD idea in mind, if this whole project gets too complicated.

Another question though: my HDD currently has two partitions (Windows 7, and the Mac OS). If I were to clone my HDD to a new SSD, would both partitions work (assuming I'll be booting up from the optical bay)? Also, what would I need to do to the HDD contents afterward (to avoid an overlap of data)?

Thanks again,


If you are using BootCamp it's not so simple. Remember only the primary drive can support it.

Frankly, I've given up using cloning software and just stick with Apple's migration tools as they are faster and more reliable.

If you have a dual boot setup you may want just to manually create the partitions and re-install Windows and let the Windows installer migrate your user accounts and apps over.


Ah, alright. Thanks Dan for the information about the dual boot.

I've also just about given up on finding ways to clone the BootCamp partition. Seems like a lost cause, haha.


Add a comment

Add your answer

J J will be eternally grateful.
View Statistics:

Past 24 Hours: 0

Past 7 Days: 0

Past 30 Days: 2

All Time: 79