Archive for November, 2012

My DIY Fusion Drive

Fusion Drive!

Ever since reading about Apple’s new “Fusion Drive” announcement, I’ve been intrigued.  The idea of adding an SSD of substantial size to a hard drive, with the OS performing behind-the-scenes data shuffling so the things you need more often are on the SSD, is pretty attractive.  Add to that the fact that it works on the block level, not just the file level, and you have a serious advancement.

In performing additional research about it, I found some reports that agree with the initial DIY assessments, and one report that disputes the results, saying that they never saw files move back and forth.  They’re suggestion was to just buy a small SSD, install the OS on it, and link your Photos, Music, etc to your secondary hard drive.  While they brought up the need to do things like this (if, for example, you work on large video files, and want to edit them on the SSD to save time), I can’t say that is the best route.  If it were business critical, I’d just spend the money on a large SSD and be done with it.

Anyhow, as luck would have it, I’d been toying with the idea of buying one of the kits online to add a SSD to my 2011 Mac Mini.  So, I pulled the trigger on that order, and within a few days, had a sale on the Crucial m4 128 GB drive, down to just over $70, so I ordered that as well.

The Hard Work

Yesterday, I had both of the components in hand, so I performed the delicate operation.  I am not new to opening up my machines, having previously built numerous PCs, along with hard drive swaps in an original Mac mini and the first model of Intel iMac.  Aside from those, my only other mac internal experience has been upgrading RAM in some of the previous generation Mac minis (which wasn’t bad, but far more involved than the 2011 mac mini RAM upgrade process).

This operation took me probably a full hour to perform.  Maybe a bit longer.  Doing this is serious business.  If you are considering this yourself, watch the install video.  Then, watch it again.  Installing a second drive involves removing almost every single component of the Mac mini from the chassis.  The connectors and cables are very delicate.  I felt like I was dangerously close to breaking something at numerous points throughout the process.

The instructions from Other World Computing (included in my kit) were excellent, except for one minor point.  Step 1 on the Assembly process says to replace the two Torx T6 screws to attach the drive housing to the chassis.  Try as I might, the screw on the right side was too long.  After trying for several minutes, I sat back and reviewed the dis-assembly instructions.  It was then that I realized that you must reinstall the power supply before attaching the right side screw, since it should go through a tab that sticks out from the power supply.  The instructions I was following start the process of installing the power supply in step 2, finishing the power supply install in step 6.  OWC should really fix that.

Other installation issues:

  • Installing the SSD in the drive is easy, but be sure to screw the screws in far enough.  If your screws aren’t in pretty far, they will bump up against the inside of the chassis, keeping you from properly lining up the drive housing with the screw holes in the chassis.
  • Installing the hard drive is trickier than it looks in the videos.  That step alone took me 10-15 minutes, mostly because its very hard to ensure you have it in the right spot.  The manual suggests placing a screwdriver in one of the screw holes on the side of the drive that’s visible to help position the drive.  That didn’t seem to help me much.  I think I finally got it in on my second attempt to position it while the chassis was sitting upright (so gravity could help me position it, a little).

Prior to installation:

1. I used SuperDuper to make a clone of my boot drive.
2. Made sure my Time Machine backup was up-to-date.
3. I created a bootable Mountain Lion 10.8.2 USB drive.

After installation:

1. I booted normally (against the hard drive).
2. I downloaded the latest Crucial m4 firmware, burned it to a CD ROM, and booted to it to update the firmware using my external DVD drive.  (ALWAYS upgrade your SSD firmware!  There are some issues with older firmware and the most recent version is said to improve performance by as much as 25%.)
3. I installed TrimEnabler, turned Trim on and rebooted to enable Trim on the SSD.  (Run it after the reboot to ensure it’s supported with your SSD!)
4. Updated my Time Machine backup and my SuperDuper clone one last time.

OS Re-installation:

1. I followed the instructions on to enable Fusion (steps 4 – 7).
2. I tried booting from my 10.8.2 USB stick and restoring a Time Machine backup to my Fusion drive twice, but it failed each time within just a few minutes of starting.
3. Finally, I did a clean install and restored my system from Time Machine after installing the OS.  Perhaps #2 is a bug related to Fusion drives.
4. Using Trim Enabler, I saw that TRIM wasn’t enabled, so I turned it back on again and rebooted.  After that, Trim was enabled!


I don’t have any real metrics to show.  The various tools to measure speed are mostly useless here anyhow, since anything written to the drive will go to the SSD first, and most tools would probably then read what they just wrote, meaning they’d be reading from the SSD as well.

My SSD is the 128 GB Crucial M4, and the hard drive is a 500 GB Toshiba (5400 RPM) – the original drive that came with my 2011 Mac mini (the mid-level model with discrete graphics).  My Fusion drive is 614.48 GB (I left about 10 GB free for the recovery partition).  I’m using 342.95 GB, so I’m far above the 128 GB of my SSD.

Caution:  Don’t use the Disk Utility that comes with 10.8.2 for anything to do with the Fusion drive.  When looking at it in Disk Utility, it sees the name of my LVM (Fusion) and the name of the partition, but it shows it as the 500 GB drive.  The next version of 10.8 will probably have a new version that sees Fusion drives appropriately.

Noticeable Changes:

My boot time is considerably faster now.  Like 1/3rd or 1/4th the previous boot time.

Resuming and Suspending my VMware Fusion VMs is substantially faster than before.  This is something that I hoped to see, but was skeptical.  According to initial reports about Fusion, this works on the block level, so it’s possible that just the portions of the VM disk files that are frequently accessed are on the SSD, with the portions that don’t get used often residing on the hard drive.

Applications seem to launch instantly.  Most apps have their window on screen before the dock icon completes the first “bounce”.  Apps like Civ V still seem to take their time on the “Loading” screen, but apps I use on a daily basis are very snappy.  Perhaps if I start playing Civ V again, it will speed up too?


My results are completely subjective, but given the nature of the Fusion drive, it’s difficult to test.

With that in mind, so far I really like it.  My system seems snappier and more responsive with my DIY Fusion drive.

It looks like a good way for a relatively casual user to get most of the performance benefits of an SSD without the high cost of getting an SSD big enough to hold everything.  At least, if you don’t buy it from Apple.  They are currently charging $250 extra for a drive with a street price of about $110 (or even under $100 on sale).


1. There is not currently a way to see how your files are laid out across the drives.  Not really a Con, unless you are a control freak.  It just would be really nice to have some evidence that the Fusion process is moving data around.
2. Since the Fusion drive is a combination of two physical drives, you are doubling the chance of catastrophic drive failure.  A single drive failing will cause you to lose all the data on your Fusion drive.  This just makes it all that more important to keep your data backed up.

November 21, 2012 at 11:31 pm 2 comments


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