OWC's Mercury Rack Pro is a compact 1U desktop or rack mount external RAID storage solution for the Mac. The Mercury Rack Pro provides a quad interface using eSATA, FireWire 800, FireWire 400, or USB 3.0. The USB port is backward compatible to USB 2; the eSATA port uses port multiplier technology to access the four drives when used in a non-RAID configuration.
The Mercury Rack Pro supports hardware-based RAID 0, RAID 1, RAID 3, RAID 5, and RAID 10. Although not technically a RAID type, the Mercury Rack Pro also supports SPAN. It can also access each drive independently.
Mercury Rack Pro Raid Review - Overview
The Mercury Rack Pro is a 1U rack mount storage solution that incorporates four drive bays as well as an internal power supply, all designed to fit in a standard 19-inch rack that takes up 1U height. And while most Mercury Rack Pros will spend their days rack mounted, the rack mounting ears can be detached, and desktop feet (included) can be attached, turning the Mercury Rack Pro into an external desktop RAID storage solution.
The Mercury Rack Pro comes equipped with a quad interface that supports connections to the Mac using eSATA, FireWire 400, FireWire 800, or USB 3.0 (USB 2.0 compatible). All ports support hot plugging, although you need to be sure that the eSATA port you're connecting to fully supports hot plugging; not all do.
The Mercury Rack Pro uses a single internal power supply to provide power for all of the device's needs. There is no capability to hot swap or even swap the internal power supply, but this is to be expected from an external storage solution in this price range.
The Mercury Rack Pro is a hardware-based RAID system that can be configured using three slide switches on the back of the unit. OWC also supplies a software-based RAID Manager that you can use to monitor and configure the RAID settings from your Mac. At the time of this review, the RAID Manager software was still in beta; I performed most of my testing using the hardware-based system.
The Mercury Rack Pro uses four tray-less drive bays that allow the user to easily insert or remove drives at any time. It also supports hot plugging.
Mercury Rack Pro Raid Review - Setup
I chose to use the Mercury Rack Pro in a desktop configuration, so I could easily make changes as I tested. This configuration also quickly answered a question I always ask of external storage systems: How loud is it?
Although the Mercury Rack Pro uses three internal fans, the actual noise level was very low, adding little to the ambient noise in my small home office. If you're considering using the Mercury Rack Pro on your desk in a home or studio environment, I think you'll easily be able to live with the very small additional noise level.
Installing the Hard Drives
The Mercury Rack Pro is sold in multiple configurations, from 2 TB to 12 TB. OWC provided four Hitachi 500 GB drives for testing, representing what would be included in the standard 2 TB configuration. The drives are supplied in their own packaging and must be installed in the Mercury Rack Pro.
Installation was simple, indicating how easy it will be to manage and replace drives in the device. To access the drive bays, the front aluminum panel is flipped down, exposing the four drive bays. Each drive bay has a small latch above it that serves as a drive ejection and drive capture latch. After opening a drive bay's latch, you gently push the bare hard drive into the drive bay until the latch is engaged by the drive. After that, gently closing the latch locks the drive in place.
Connecting the Mercury Rack Pro to the Mac
I'll be using a 2010 Mac Pro as my test bed. You can read about the specific configurations of the Mac Pro I'm using on page 2 of Mac Pro Review.
I chose to use the eSATA port on the Mercury Rack Pro for my testing. The eSATA port supports up to 300 MB/s transfer rate, the fastest of the available ports. The Mercury Rack Pro will connect to a DAT Optic eSATA PCIe8 card installed in the Mac Pro. The DAT Optic card supports a port multiplier on each of its four external eSATA ports. An eSATA port with port multiplier technology is required to access all of the possible configurations of the Mercury Rack Pro.
Mercury Rack Pro Raid Review - Selecting a RAID Setting
The Mercury Rack Pro supports five RAID settings (RAID 0, RAID 1, RAID 3, RAID 5, and RAID 10). It also supports SPAN, which combines all of the installed drives into one big disk, and Independent, which allows you to access each drive separately. It's this last configuration mode that requires the port multiplier technology when connected by the eSATA port.
Selecting a RAID configuration using the switches on the Mercury Rack Pro turned out to be not as easy as it looked. The process is broken into two steps: clear the existing configuration and apply a new configuration. Clearing the configuration is accomplished by powering the Mercury Rack Pro off, setting the three RAID selection switches on the back of the unit to the clear (all down) position, holding the Set button in while pressing the power on button, and continuing to hold the Set button until the unit beeps and all drive displays stop flashing.
Once you have cleared the configuration, you can power the unit off, use the RAID switches to select a new RAID configuration, and then repeat the process (hold the Set button while powering on the unit).
While the process is a little cumbersome, it became downright annoying for two reasons. First, the power and Set buttons are crammed next to each other, and I couldn't get two of my big fingers into the space to press both of them. I was forced to find and use a small pointed stick to press the power button while I used a finger to hold the Set button in. The second reason I found it annoying was that I had to try every RAID configuration offered, and do so multiple times during the testing.
Most users only need to configure the RAID settings once, however, so the cramped quarters for the two switches won't be as much of a problem.
Luckily, the RAID Manager software lets you configure the RAID settings from the Mac, so once the software is out of beta, I'm sure it will be the preferred method for setting up the Mercury Rack Pro.
Mercury Rack Pro Raid Review - Formatting the Drives
Any time you change RAID settings, you will need to format the drive before you can use it. This is an important consideration. If you have data on a current RAID drive, changing the RAID type will make the data unavailable and force the drive to be reformatted.
Because this is a hardware-based RAID, formatting is actually quite simple and uses the already familiar Disk Utility, which is included with the Mac. Because the Mac sees the Mercury Rack Pro as just another external hard drive(s), you don't need to worry about special RAID drivers or compatibility, should you move the Mercury Rack Pro to another Mac. This is a much better way to format and use RAID arrays than systems that use custom drivers and formatting tools.
Once you complete the formatting, the Mercury Rack Pro is ready for use. Continue on to page 2 to see how well the Mercury Rack Pro did in our performance testing.