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Extending MacBook Pro speed and capacity with dual drive upgrades

Apple's MacBook Pro has only one hard-drive slot, but you can replace the optical drive with a bracket to hold another hard drive, and in doing so put a small and cheaper SSD in for a boot drive, to couple with a larger mechanical data drive.

Topher Kessler MacFixIt Editor
Topher, an avid Mac user for the past 15 years, has been a contributing author to MacFixIt since the spring of 2008. One of his passions is troubleshooting Mac problems and making the best use of Macs and Apple hardware at home and in the workplace.
Topher Kessler
16 min read

There is no doubt that when compared to a mechanical hard drive, the new solid state drive (SSD) technology is by far superior in terms of speed. Data access and throughput can be well above 4x faster than a contemporary mechanical drive, and using it as your main boot drive widens a major bottleneck, resulting in exceptionally quick boot-ups, application launches, sleep and wake events, and shutdowns. Beyond speed, the drives also have a number of additional perks, including cooler operation than most mechanical drives, power efficiency resulting in longer battery life for laptops, silent operation, and higher tolerance for abuse since there is no need to protect moving mechanical components.

Unfortunately along with its benefits, SSD technology is currently very pricy, to the point where it may not be feasible to upgrade a system with a comparably sized drive. This is especially true if you need to maintain large storage capacity on your system. For example, the average price of a 500GB mechanical drive is currently around $40 whereas a 500GB SSD is over 20x more expensive at around $850.

Because price may be a limiting factor for upgrading, one option is to create a hybrid SSD environment to give yourself the best of both worlds: a small and fast SSD drive to hold your system and applications, and a larger mechanical drive to hold your larger personal data. Apple offers this as a configuration option for new iMac and Mac Pro systems, but so far Apple's laptops have not had the capability of holding more than one hard drive, at least with the default configuration.

To overcome this limitation for the MacBook Pro, beside dishing out the money for a large SSD you can take two routes. The first is to use a larger external drive along with a smaller internal SSD, but this may not be the best option (especially for laptops) because external drives are slower, more prone to breaking, and will require you to lug them around to keep attached to your system.

The second option is a more practical one, which is to replace the optical drive in the system with a bracket that can hold a second hard drive in its place. This will allow you to take advantage of a small and cheaper SSD drive, while maintaining a second larger mechanical drive in the system. Being an unconventional approach this may seem a bit odd at first, but there are three reasons why someone would want to do this:

  1. Rarely use the optical drive
    Even though optical media is still widely used, most content is available via download and can be placed on flash drives as disk images if you need to install it. Even Apple's next operating system, Lion, will be available only as a download from the App store that will install without the need for optical media. Movies and music are all available online, and many times people end up using their optical drives only for backup purposes instead of for active daily use. This is not to say people do not use them, but rather that the optical drive is becoming progressively less used and you can get by without it.

  2. Need for speed
    Even the fastest mechanical drive is far slower than SSD options, so the need for a snappy OS experience requires more throughput, especially as applications and system software gain larger and larger footprints. Even items like system icons have gone from 16x16 or 32x32 pixels to 512x512 pixels or higher to make the OS look pretty, and all these larger resources together take more drive space and RAM, and therefore require more throughput to load and manage in memory. As a result, even by compensating and getting more RAM, a system will still be paging large amounts of RAM data to the hard drive, and speeding this process up will greatly increase RAM efficiency.

  3. Cost vs performance
    As I mentioned above, SSD prices are quite high, but in addition, the majority of storage on large SSD drives will go relatively unused for most people, and even Intel has shown that people can get by fine with smaller SSD sizes. In Intel's latest Z68 chipset, the SSD caching technology uses an SSD drive of up to 60GB to store frequently accessed items stored on slower mechanical drives. What this demonstrates is that most people do not usually have more than 60GB of regularly accessed items on their hard drives, and therefore should be able to get a fast experience by implementing a smaller SSD drive than one that will hold all of their data.

For my uses I meet all of these criteria, so recently I decided to give this setup a try in my MacBook Pro. There are a variety of SSD manufacturers out there, and the options for a drive mounting bracket include OptiBay and Other World Computing. Other World Computing has been offering upgrade options and add-ons for Mac systems for over 20 years and has gained a reputation for offering well-made and reliable options for Mac systems, so I was content with trying three of the upgrade kits they offer:

  1. The DIY "On-the-Go" Laptop Drive Upgrade kit
    This kit is basically a hard-drive upgrade that includes an external enclosure to turn your old hard drive into an external drive. Optionally you can just use the included drive with the enclosure to get a larger external drive to use (though this would defeat the purpose of having purchased the upgrade drive for your system). The kit also comes with a Torx and Phillips driver set along with some plastic pry bars that help in assembling the enclosure and installing the drive on your system. The kit I chose included a 750GB Seagate Momentus 7,200rpm hard drive.

    I primarily chose OWC's "On-the-Go" option because it has options for supporting multiple drive interfaces (combinations of Firewire 400/800 and USB 2), OWC also offers a "Express" enclosure that is either USB 2 or USB 3 (though USB 3 is not yet available from Apple on Mac systems). Keep in mind you can use any 2.5-inch external drive enclosure for this upgrade, but bundling it all with one purchase might be an easier route.

  2. Data Doubler Kit
    This kit is the main part of the upgrade because it allows two hard drives to be put in the system at once. It offers a sturdy mount for 2.5-inch drives in the optical bay of the MacBook Pro (though there are options for the MacBook and Mac Mini as well). This kit can come with just the bracket, or you can include your choice of mechanical drive or SSD. For my hybrid setup I chose the kit with the 115GB Mercury Elite SSD.

  3. Optical-drive enclosure
    After installing the Data Doubler you are left with the bare optical drive that came with your system, so instead of putting it on the shelf or auctioning it off online, you can turn it into an external drive by using OWC's value-line superslim optical-drive enclosure. While more of an optional component in my point of view, OWC does offer it at a discounted price when you purchase the Data Doubler kit.

With these three options, the total price ends up being $449.97, whereas doubling the SSD capacity by only getting a single 240GB bare drive upgrade would be almost exactly the same price at $449.99. Granted, prices will always fluctuate and SSD prices will undoubtedly drop, but with the upgrade kits I got ample SSD storage for the OS and applications I use, and the option to either keep my original drive for data storage (and use the 750GB drive for external storage), or upgrade to the 750GB drive that came with the DIY kit.

In order to take full advantage of the upgrade, I installed both the 750GB drive and the 115GB SSD in the system, which results in a full 865GB of internal storage, along with both an external hard drive and an external optical drive.

The upgrade process: Some assembly required

It is important that the first thing to do before performing any hardware modification to your system is to check your warranty. If your system is out of warranty then you should be good to go, but if not, then you will very likely void your warranty by doing anything besides upgrading specific components (RAM, battery, and perhaps the hard drive). Apple very likely will not cover a system from which the optical drive has been removed, so be sure you understand these risks before you begin.

Now for the fun part: installing the devices. Computer manufacturers do not offer separate components in boxes that you would have to install by yourself, with good reason: opening a computer chassis (especially for a laptop) and removing components can be a delicate and daunting task for someone who is not familiar with working on computers. OWC does offer good step-by-step instruction booklets in the upgrade kits, as well as invaluable online video guides for how to perform the upgrade, but even with these, some people may find the upgrade a bit challenging.

Not only does the upgrade require you to take apart delicate components of your computer, but it also requires you to assemble the external enclosures. This is ultimately not a difficult task and overall is a bit fun to do, but it does add to the time needed to get things up and running so if you are in a hurry or do not feel up to the task then it may be best to have the procedure done for you (OWC offers an installation service of around $80-100 for this particular upgrade).

If you still want to perform the upgrade yourself, then back up your system before doing anything. Even the most computer-savvy technician may make a mistake, such as not properly grounding themselves when tampering with components or even improperly connecting a drive. Therefore, even though it may be tempting to flip your system over on the living room carpet and get to work installing your upgrade, this is the last thing you want to do. Not only can you lose small parts but you can also discharge static into the system that may damage sensitive integrated circuits, ROM, RAM, and controller chips. Be sure you work on a static-free surface (a clean wood desk is best) and properly ground your body to the computer chassis throughout the installation procedure either by continually touching it, or by using a wrist grounding cable (commonly sold at most electronics shops).

Stage 1: Replacing the optical drive

OWC's Data Doubler bracket is a neat idea that turns your optical-drive bay into an additional hard drive bay in which you can put basically any 2.5-inch drive device. With both of my upgrade kits I had the option of putting either the new 750GB drive or the 115GB SSD in this bay, so I chose to go with the SSD.

Opening the computer was fairly easy to do with the included screwdriver set (though I do recommend using well-made and properly sized drivers to avoid stripping screws). Using the included instructions booklet and OWC's online videos the back cover came off rather easily, showing the RAM and hard-drive bays for easy access to those upgrades, but the optical drive was a little more of a challenge to get out because it is tucked under a delicate ribbon cable for the display, and taped down to the side of the optical drive. Nevertheless, after gently removing the required anchoring screws, with a little wiggling, the drive slid right out. OWC does mention unplugging the delicate display ribbon cable, which is advised for added precaution; however, I found this step was not needed; the drive slid out quite easily.

The next step was assembling the bracket and SSD drive, which was pretty straightforward. The bracket holds the SSD on one side, and while this is more than adequate for holding the drive, there is plenty of room in the bracket to brace the other side of the drive as well. An additional observation is that while the included screws do hold the drive in the bracket just fine, only a couple of threads actually hold the drive in place and it would be more comforting to have either longer screws or to have the drive braced on the opposite side as well. Nevertheless, after tapping and tugging the drive in the bracket, it appeared to be firmly mounted.

With the optical drive out and bracket assembled, it was now a matter of placing the bracket in the machine. This was fairly straightforward since the bracket is the same shape and size as the optical drive; however, the bracket's mounting points were a bit thicker than those of the optical drive (likely because the bracket's plastic is not as strong as the optical drive's aluminum mounting points), so OWC includes some longer screws to use where needed. After the bracket was installed, the delicate ribbon cable was taped back on the drive, I replaced some of the additional shielding tape that was removed in the process, and that part was complete.

Stage 2: Replacing the standard drive

This step was fairly straightforward, especially since the system was already open and Apple makes replacing the drive rather simple by unscrewing the two screws on the drive's anchoring bracket, lifting it out by the attached tape tabs, and disconnecting it. Apple's hard drives contain four positioning feet that are just special Torx screws, so after placing them on the new drive, everything was ready to reassemble. This procedure was for the 17-inch MacBook Pro that does not have an access latch, but for the 13-inch or 15-inch systems the process for replacing the hard drive is even easier.

Stage 3: Assembling the external hard-drive enclosure

OWC's Mercury On-the-Go enclosure allows the old hard drive to be used as an external drive, not only to have a spare external hard drive for data storage but also for easy transfer of data after installing the new drive. If you do not want to turn your drive into an external hard drive, then you can get by with a cheaper drive adapter cable to quickly and temporarily attach the drive for the data transfer.

The On-the-Go enclosure came in several separate components: A drive controller board, a heat sink, and a plastic hollow chassis with an adapter plate to fit the type of on-the-go controller board you have (there are about five different models that have different connection configurations). While the overall assemble was simple, some steps were a little cumbersome. Attaching the drive to the controller board was easy, as was inserting everything into the chassis; however, screwing the assembled board to the chassis took a little creativity. The internal components aligned to their mounting screw holes properly, but upon inverting the assembly to screw the board down, the components dropped far enough away so that the inserted screws would not catch. The screws ultimately had to be installed by holding the assembly over my head, and after dropping a screw once or twice I finally got it tightened up.

Stage 4: Assembling the external optical drive

The final stage was to make use of Apple's optical drive I had removed. OWC's superslim optical-drive enclosure offers a quick way to turn the internal optical drive into a USB drive, and was fairly easy to get together. The chassis slides apart and contains a small controller board and mounting holes that you line up and screw in. The one source of confusion I saw in this kit was it came with two types of screws (some with a shoulder and others without), but the instructions did not differentiate between the two types. The screw with the shoulder prevents you from driving its beveled head in too far when mounting the optical drive to the chassis, which may potentially snap it the enclosure's mount points (Update, June 22, 1:53PM PST: Since this article was written OWC has released a video tutorial for the superslim drive that shows which screws go where). Another observation about the drive is that while stylish and lightweight, the plastic enclosure does not feel very rugged. While it operates just fine, it would be nice to have it in aluminum even if it weighs a little more. Regardless of this detail, the drive came together nicely and was ready to use.

Making use of it all

With the installation and assembly complete, now it was time to test it all out and transfer data. Because the OS installation and data on my previous hard drive was well over the 115GB capacity of the SSD I had to sort through what I did and did not need, not only to allow things to fit on the drive, but also to ensure there was ample room for virtual memory and future growth.

To do this, I initially booted off the external drive that contained my old hard drive. I did not use Time Machine because there was inadequate space for all my data on the SSD, but if you have an SSD that has enough capacity then this is one route you can take. Instead, I used Carbon Copy Cloner (OWC includes this with the Data Doubler kit), which allows you to mirror one drive to another but also has the option to uncheck items you do not want to copy.

When complete, the clone size ended up being 68.95GB of data, which took just over an hour to finish, after which I set the boot drive in the system preferences, restarted, and was up and running. The only remaining step was to put the items not cloned to the SSD onto the 750GB drive, and the upgrade was complete!


The first thing I noticed after upgrading was, it is fast! Even though reviewers and benchmarks claim SSD performance is very fast, and even if you have tried SSD drives on other systems in stores and elsewhere, seeing your own setup with its various slowdowns suddenly booting much quicker and loading items with barely any delay brings a certain and unexpected level of satisfaction. It is great to now see most applications load in OS X with only one bounce in the Dock, and while a few others may take two to three bounces, but rarely will one take longer than that. This contrasts sharply to most applications having previously bounced numerous times during launch.

Some applications required settings adjustments to be reassociated with the libraries and data files that were now on the secondary data drive. When launched, most of these applications such as iTunes, iPhoto, and Parallels Desktop either loaded default configurations or gave me an error stating my library could not be found, but after making a few changes these programs were working again.

Overall not only did the SSD drive offer faster speed, but by taking the burden of system management off the mechanical drive, it made the use of that drive faster as well. One of the tools I regularly use is Parallels Desktop, and upon starting it I noticed the virtual machine loaded much faster than previously, even though it was located on the slower drive. In addition, other large items and libraries also loaded quickly in other applications. This boost in speed has to do with two main factors. The first is that the OS and Parallels software are located on the fast SSD drive, and therefore the use of virtual memory and memory management is exceptionally quick. The second is that the throughput of the drive is solely dedicated to reading the data, instead of being used for other tasks such as loading OS components, other applications, and manage virtual memory. This speed increase can be seen in systems with two mechanical drives, but when coupled with the SSD drive it is a bit more apparent.

Not only did this setup speed the system, but it increased battery life as well. Because the mechanical drive is rarely accessed anymore, it tends to stay in sleep longer, resulting in about 30 minutes to an hour extra battery life for the system, even with two drives in the system. As an additional way to increase battery life, the data drive can be unmounted using Disk Utility to prevent it from being accessed at all; however, this would only need to be done if extended battery life is crucial.

One thing to note about pairing a third-party SSD with Apple's systems is that currently the drive reconditioning command "TRIM" that clears and prepares unused SSD memory for new data, is not supported. While the drive does support this option, Apple currently only enables it on Apple-branded SSD devices. Nevertheless, with tools like TRIM Support Enabler you can get OS X to enable TRIM for the external drive.

The last observations were around the optical drive enclosure, and here I did run into a couple of roadblocks. OWC includes a dual-head cable for some systems that may not have enough power in one USB port to power the drive (not needed in my case), and while drive loaded and mounted DVDs just fine, I did run into a problem when trying to play movies off of it. Inserting a DVD movie showed the disc loading correctly and being recognized as a movie by the system since DVD Player automatically launched; however, DVD Player then displayed an error stating a proper DVD device could not be found, and promptly quit when I closed the error window. Unfortunately even though OWC's drive enclosure can support DVDs, your system may run into this problem. Nevertheless, there are some workarounds, as I explained in a on overcoming this issue in OS X.

The next issue with the external drive is that the system's eject key no longer works. Apple's eject key is mapped to work with internal drives, and external drives by default must be manually ejected. This is a bit frustrating to have, since when using optical media I enjoy being able to quickly eject the disc regardless of the application I am in. Luckily there are several ways to overcome this, which include remapping the key using a utility like KeyRemap4MacBook, or you can assign a new keyboard shortcut to a script or that will eject the external drive for you.

Final thoughts

Overall, despite its seeming complexity, the upgrade is definitely worth it, provided you have the time, patience, and trust in yourself to install the SSD and drive bracket, and then reconfigure your system to use both drives properly. While the upgrade may be slightly difficult to install on your own, requires some reconfiguration of the system, and removes the optical drive, if you are up for it, then you will end up with a much snappier system with higher storage capacity, longer battery life, and with two other hardware devices that can be used on other systems if needed--all for the same price as OWC's 240GB SSD upgrade.

In addition, while I chose these particular drives for the upgrade, OWC offers smaller and larger options for each drive type, so you can pick and choose the sizes that will fit your needs: two mechanical drives, a hybrid setup as I did here, or even put two SSDs. These options make it easy to store data, create an internal clone or other backup option for yourself (partitioning the larger internal drive will work for this), or you can even set the drives to be in a software RAID configuration, if desired.

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