I've been looking for a cost-effective RAID solution to add additional drives to the Mac Pro. MaxUpgrades has a nice caddy that will allow up to 4x drives in the optical bays, but since I use both of the bays I needed something else. After doing some research on firewire 800 vs. usb 2 vs. eSATA speeds, I decided to go with OWC's external eSATA case, which house 2x drives. In order for this to work, I also had to purchase an eSATA extender bracket, which plugs into the 2x unused Mac Pro slots and provides two plugs in a slot at the rear of the machine. Total cost is ~$93, and will provide faster speeds than an external firewire enclosure. The CRITICAL thing to remember, is that these drives are not hot-swappable, and if they are unplugged while live, kiss your system goodbye. My workspace is somewhat boxed off, so hopefully this won't be an issue. First Part: eSATA enclosure After unscrewing 4 screws on the bottom of the enclosure, the middle slides out, where you mount your two SATA drives. The enclosure comes with the option of a power LED. I chose to install it as a visual reminder that it's connected to the Mac Pro. To do so, you just swap the default power cable with the cable that includes the LED. Place a small grommet in the location of your choice (3 possible) and run the LED there. Front plate goes back on... ... and slides back into the enclosure. This is a pic of the rear from OWC. The only options are eSATA cables, no firewire or USB. Since this is a stationary enclosure, that's fine with me. The power cable snaps and holds pretty well, compared to other enclosures I've had in the past where the cable pops out with the slightest tug. The fan noise is low, but not silent. Average temps of the drives was around 41C. Second Part: eSATA bracket / extender This is the most difficult step of the install. There are two heads, one at 90-degrees that you must plug into the unused SATA ports on the motherboard. The tricky thing is that these ports are sitting behind the plastic shield of the front fan/cardslot guide. The instruction says to remove a lot of parts from your Mac Pro to have full access to the motherboard. BUT, many Mac Pros have their screws bonded to the case and cannot be removed easily. Mine is one of those Mac Pros. Since I installed this at ~3:00am, I was tired and didn't want to bother finding another way to remove the screws. So I got a small flashlight (cell phone light), laid the mac pro down, and reached in there with my hands trying to plug them in. The first plug (90-degree angle) is easier to put in, since the cut-out on the plastic guide will allow you to move further in. The second takes a bit of finessing, but here's something you can try: hold the cable and bend the head at a 160-degree angle so it's bent slightly downward. Then tweak it so it also slants slightly down to the right like this \ This will let you place the head over the slot a bit easier. Once you have a part of the head over the slot, you can use a flat piece of metal (I used the PCI port piece from the back that the bracket replaced) and gently push it down into the slot. The nice thing is that the slot has the protruding groove facing towards you, so you can just align the plug with the groove and push down with the bracket piece. Cables galore. All Done After rebooting, I set up my drives to the following, using a similar setup that I found at MacProJournal.com So far so good. Having the RAID-0 across the four drives is a great boost. I'm still not sure about having my DATA sit on the same drives as the RAID-0, on a different partition. In the even of 1 drive failure, wouldn't the whole RAID-0 AND RAID-10 go down? So for now I'm keeping critical data backed up on another drive in the eSATA.