OWC Mercury Accelsior PCIe SSD

Over four years ago I purchased a Mac Pro. I was pretty happy with it at the time—indeed, I wrote:
For now, here's my initial impression: the Mac Pro is fast. It's the snappiest I've seen Mac OS X, which, in my opinion, can be a bit of a dog on my MacBook Pro.
Over time, a few things have happened. Firstly, I am certain that my expectations have increased. My wife has had a MacBook Air for a couple of years, and I've had one since late 2011. Solid state drives are a whole new level of fast. I can't even use my ageing MacBook Pro any more—it's just too slow. Screen real estate was what I thought would be the biggest trade-off in moving to the Air (from 17 inches to 13 inches), but the MacBook Pro is just so eclipsed by the speed of the Air that the screen size is basically irrelevant.

Secondly, I'm starting to buy the argument that's being posed in various places that something is deeply broken in OS X memory management. I've been seeing most of the features mentioned in that post for some time, especially "frequent beachballs, particularly when switching applications and sometimes even tabs", and "general overall slowness and poor UI responsiveness". Safari regularly takes 30 seconds or more to launch to a blank tab. Opening a Terminal window takes in the order of 10-20 seconds. And all the while my main disk is pathologically thrashing. It basically never stops moving. And this is a machine with 12G of RAM. The Mac Pro is now the "bit of a dog" that was the laptop four years ago—with 8 cores and a single system disk (and a separate storage disk, 1T total), it's completely disk-bound.

So, I did something about it. Last Monday I ordered an OWC 480G Mercury Accelsior PCI Express Solid State Drive from Macfixit Australia, and by Friday afternoon I was installing it in the spare x16 PCI Express revision 2.0 slot in the Mac Pro. The rest of the evening went like this:
  1. After booting the machine, OS X detected the new disk, but complained it could not be read—completely expected, as it had not been formatted. Using Disk Utility I formatted it as a single partition Mac OS Extended (Journaled) disk.
  2. I had intended to use Disk Utility's "Restore" feature (somewhat oddly named for this use) to clone the existing 500G (about 380G used) boot disk onto the SSD. With no attempt at explanation, Disk Utility informed me that it couldn't clone a bootable disk, so that was the end of that.
  3. I downloaded SuperDuper! and started a standard "Backup - all files" backup. (I wish someone would just call it cloning. That's a pretty standard term.) This took about 5 or 6 hours.
  4. I rebooted the machine with the Option key held down, assuming I would be able to select a boot disk. Instead I was presented with two options: "Macintosh HD", the existing boot disk, and "Recovery HD"—apparently a new Lion feature, about which I knew nothing. (Obviously I was hoping to be able to select to boot from the SSD. I don't know whether there was another key I was supposed to be pressing, or whether you just can't do that.) After quitting the recovery application, I was able to select a boot disk, and booted off the SSD.
  5. The machine is still up, and still running off the SSD as boot disk. I have set the SSD as the default boot disk using System Preferences. Once I'm satisfied everything is working smoothly, I'll format the old boot disk, freeing up some 500G of spare storage, which is nice.
The Mac Pro is now blazing. It's also noticeably quieter without the endless thrashing of the old spinning disk. You can read a Macworld review for the numbers, but the qualitative summary is that this is almost certainly as good an upgrade as when I went from 4G to 12G of RAM. The SSD is pricey (just over $A 1,000 with shipping), but cheaper than buying a new Mac.


  1. Hi, Really great effort. Everyone must read this article. Thanks for sharing.

  2. OWC Mercury Accelsior PCIe SSD. Over four years ago I purchased a Mac Pro. I was pretty happy with it at the time—indeed, I wrote: For now ... pciessd.blogspot.com


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