Samsung 840 EVO 750GB SSD & MacBook Pro: Disk Speed Blues


[section_title title=”The Process”]

The Process

Out Of The Box

The simple shipping box contains the drive itself, an installation guide, and the obligatory CD-ROM containing Windows-only software, which most Windows users will probably bin anyway in favour of downloading the latest software from the Samsung website.

Samsung must have realised that a solid state disk is not the most tactile of items, light as it is, so have fashioned a pleasing, monolithic grey cover around it to give it a sense of gravitas, and presumably better thermal cooling properties. This is about as exciting as it’s going to get for a solid state component you’ll never see once installed, but you do get the impression they’ve made a bit of effort for your money.

That’s about it for the EVO version. PRO purchasers also get two “Samsung SSD Activated”stickers for their case. We Mac users tend not to go for stickers anyway…


Bearing in mind these MacBooks were never designed with SSDs in mind, early firmware teething troubles led to significant performance and reliability issues with SSD installations. Before even looking at an SSD on an older MacBook chassis you should ensure your EFI firmware is at least version 2.2. If you use Software Update, this will probably have happened without you noticing; mine turns out to be running 2.7, so no upgrade is needed. This Apple support document will tell you which EFI and SMC firmware versions your machine should be running, and how to find out which versions you have.

It’s also good practice to check the SSD firmware before migrating data, as Samsung’s firmware updates are often, but not always, non-destructive. Unfortunately, whereas Windows users get Samsung Magician to manage their drive performance and updates, us Mac users have to rely on – I’m not kidding – downloading an ISO image, burning a CD-R and booting intoDOS. DOS! I presume the old Samsung-Apple rivalry is coming into play a little here, and to be fair it does work fine in practice, but it would be nice for us Mac users to have something a little less 1980s.

However, booting from the Samsung CD image with the SSD attached by USB resulted in the SSD not being found. Therefore the firmware upgrade has to wait until the drive is installed.

Data Migration

In order to carry out the firmware upgrade and clone my existing drive, I purchased a USB 3.0 SATA enclosure, which also allows me to use the old HDD as an external drive after the upgrade.

Being an Apple operating system, not only can the boot drive be cloned without fuss, theoretically at least, but OS X Disk Utility includes this facility. However, with OS X 10.7 Lion and later versions, you must first boot from the Recovery Disk (hold Command-R whilst booting) as you can not clone the startup disk. Then run Disk Utility, select Restore for your target drive, drag the original HDD to the Source field and the target SSD to the Target field, and click Restore. Don’t get them the wrong way round… My startup disk is encrypted using FileVault, so I needed to unlock it from the Disk Utility menu prior to being able to access it.

Cloning promised to take a tedious 12 hours for 600GB of data (the speed being limited by the host’s USB 2.0 ports, meaning the SSD is pretty much idling, as much as a solid state device can idle.) However, in the event, the clone process bombed out half way through with an unhelpful “I/O Error” message. I tried again and the same thing happened at the same point.

(It’s not straightforward to access the logs in Recovery mode, so the nature of the failure wasn’t determined, but based on later experience I am confident the fault didn’t lie with the Samsung drive. It’s likely the issue was down to either the Toshiba drive, the external USB enclosure, or the serial bus itself.)

Slightly unnerved, I rebooted into OS X to make sure my Time Machine backup was up to date. Then I noticed Time Machine was taking an age to backup as well, which also set alarm bells ringing… To resolve this I booted into a Safe Mode (hold Shift after the reboot chime), which forces a filesystem check amongst other things.

I suggest with hindsight it’s a good step to check the original startup disk manually before beginning the migration process – boot into Single User Mode by restarting and holding Command-S, then type “fsck -fy” at the prompt.

Now armed with a decent backup but still without a cloned drive, I decided to swap the SSD into the Mac anyway and either clone the old to the new with the data going the opposite way down the USB cable to what I’d originally planned, or restore from Time Machine.

Replacing the HDD

For me this was the easiest part of the whole operation. As a Mac user, if you’re scared of delving around inside your Macbook’s giblets, don’t be, at least not with this Unibody model.

Be aware of static hazards; if you have an anti static wrist strap, this is a good opportunity to use it, or otherwise earth yourself and the laptop through something metallic, and avoid wearing flammable nylon leisurewear for the duration of the install.

  1. Flip your MacBook upside down with the hinge away from you.
  2. Using a Phillips size 00 screwdriver, remove all ten screws from the underside of the clamshell. Note that they are all drilled at an angle. Take great care not to strip any screw heads.
  3. Starting at the hinge, gently but firmly pull away the inner base, revealing the MacBook’s innards.
  4. You’ll see the hard drive at the front right corner. Carefully unscrew two Phillips screws on the black mounting bar adjacent to the rearmost edge of the drive. Sometimes these are captive. The front mounting bar does not need to be removed.

  1. samsung-evo-ssd-fittingRemove the rear mounting bar, and the drive will pull out using its plastic pull tab. Before you rip it out of the machine triumphantly, be sure to remove its ribbon connector: not obvious as the cable routes beneath the drive.
  2. Using a T6 screwdriver, remove all four Torx mounting bolts from the original hard drive. Insert them in the SSD. Move the self-adhesive pull tab to the SSD.


  1. Reconnect the ribbon cable to the SSD, and place it back in the drive bay.
  2. Replace the black mounting bar, clamshell and screws.

With the SSD attached to the SATA port, rather than USB, Samsung’s firmware utility will now recognise it and allow you to update if necessary. Mine was already up-to-date.

Data Migration Part 2

If your drive cloned successfully, you don’t have to worry about this second attempt. You can just turn on your MacBook and boot from the SSD. My migration wasn’t so simple.

I needed to get back into Disk Utility, but if you boot into Recovery mode with an unformatted startup disk, the Mac uses Internet Recovery, which is slow, particularly for those of us on rural Devonian broadband. Instead, connect the original startup HDD as a USB drive in the caddy, and when you hold Command-R for Recovery mode, the Mac will recognise the presence of a usable startup disk and boot far more quickly.

I ran Disk Utility and restored once more. This time it promised to take a mere 9 hours, but again, it crapped out half way through. At this point I gave up and restored from a Time Machine backup.

The down side of Time Machine is that some app logins are lost (Dropbox, for example), and many non-Apple products, such as Adobe CS4 and anything from Microsoft, will lose their licensing and require re-activation. However, the recovery process itself took a similar amount of time, and to my relief, actually worked without throwing up any further errors.

After the Time Machine restore, the system automatically reboots and you enter the world of the solid state disk.

If your previous drive was encrypted using FileVault, note that restoring from Time Machine will not carry that setting forward to the new drive. You’ll have to go into System Preferences -> Security & Privacy and enable it again.

SATA Speeds

In the early days of these MacBook Pros, users had endless problems getting their SSDs to run at 6Gbps, even though the on-board Intel 6 Series chipset theoretically supported this speed. The aforementioned firmware fix should sort this out, but it’s worth checking. Prior to installation, System Information showed my controller was capable of running at 6Gbps but had negotiated 3Gbps to the Toshiba HDD. After installation, it’s good to confirm the bus is running at the full 6Gbps.


If you are installing an SSD into the optical drive bay and keeping the original HDD, check with System Information that your controller supports 6Gbps for this bay (for example, mine doesnt).

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