Mediasonic ProBox 4 Bay Hard Drive Enclosure Review

The Problem

When I sold my Mac Pro tower and got a 2012 MacBook Air, one of the main selling points for me was the USB 3.0 and Thunderbolt high speed I/O. I cannot wait to take advantage of Thunderbolt, but those enclosures are a bit too expensive for me at this point, and the drives I have aren’t fast enough to take advantage of those speeds anyway.

I started looking around for the best way to use my existing 4 SATA hard drives from my Mac Pro with my new MacBook Air. I love everything about the Air, but I need lots of fast storage for all of my files, as well as a reliable backup system.

The Perfect Solution (or so I thought)

2 weeks ago, I found this, and decided to order it:

Mediasonic ProBox 4 Bay USB 3.0 Enclosure

For the first week or more, the enclosure was pretty much useless to me, for a number of reasons. I worked with Apple and Medisonic to come up with an answer. Mediasonic tech support was good. Their technician called me back multiple times with information as he was researching the problem. They offered a full refund, but I opted to hold on for a fix because I liked the enclosure so much.

It turns out that the main issue was with the board inside of the ProBox – it wasn’t passing the connection signal to the USB bus long enough for the MacBook Air to recognize it, preventing it from mounting the drives.

Their technician made the adjustment on a replacement board and it was shipped to me promptly. It arrived a few days later and was very easy to install. 12 screws and 10 minutes later, I tried again.

Step 1. Remove the six back plate screws

Step 2. Unplug the fan and remove 6 screws from the board

Step 3. Unplug the data cable, remove the old board, and reverse the process with new board

The Fixes

Success! Now the drives mount every time. All four drives are performing at their respective theoretical maximum speeds, just as fast as they were when they were internally plugged into my Mac Pro. Impressive!

However, there was another issue. When I used the right USB 3.0 port of the MacBook Air, all four drives would eject on their own every time I initiated a file transfer from one drive to another. I tried multiple USB 3.0 cables, same issue. So, I decided to try the left USB 3.0 port. Problem solved!

Left Port Good Port, Right Port Bad Port

When I plug the ProBox into the left USB 3.0 port, next to the MagSafe 2 port, the drives connect and remain connected with no issues. I have transferred about 600GB around, started a new Time Machine backup, and ran various performance tests on the drives through this enclosure. So far everything is working great.

I don’t know if I have a defective USB 3.0 port on the right side (though it worked perfectly for my Vantec NexStar3 enclosure, and other peripherals I’ve tried). It may be that the right port does not supply enough power for the multi-bay enclosure. I will be visiting an Apple Store later this month to have it checked out. In the meantime, it is working exactly as I’d hoped.

Final Thoughts

The ProBox offers a syncing feature that is supposed to sleep the drives and enclosure or turn the whole thing off when the computer goes to sleep or is disconnected. I found this feature to cause issues with drives disconnecting when I put the MacBook Air to sleep. Turning the sync mode off, however, seems to fix this for the most part. Every once in awhile when I wake up the computer, I get this error:

However, the drives come right back up, and since the computer was asleep anyway I don’t believe there is any risk of damage to the drives. More importantly, Power Nap, Air Video Server and File Sharing all work with the MacBook Air asleep. So I can access files on the external drives from other computers in the house at any time.


This enclosure is pretty darn close to the perfect storage solution for my MacBook Air. It is well built and sturdy (not plastic), it is small, the drives can slide in and out with no tools, the fan is quiet (and adjustable), and it’s very fast. However, there is no way of knowing if you’ll get one with the fixed board or not. If you do decide to order this, and your drives do not mount through USB 3.0, contact their tech support and they should be able to send you a replacement board. I am hoping they’ll get this issue sorted out so that the fix goes into immediate production.

I will be watching the ProBox closely over the next few days and I’ll report back if I notice any other issues.