Solid state storage has definitely become mainstream. More and more people are realizing that storage speed is a big bottleneck to their computer’s performance, and at the same time Solid State Drives (more commonly called SSDs) have become very affordable, especially in the smaller capacities.
After converting the boot drive in my Mac Pro to an SSD, I noticed the difference immediately in boot and shutdown time. Applications launched more quickly, and file operations sped up noticeably. But it wasn’t really until I tried using a system without an SSD that the difference really hit me. “My god, did I really used to wait so long for Photoshop to launch? And booting up, has the system crashed? No, it just takes that long for OS X to load from a hard disk.”
What is an SSD (Solid State Drive)?
As opposed to the hard disk drive (or HDD), which uses spinning magnetic discs to store and access data, a solid state drive (SSD) does not contain any moving parts.
Why is SSD better than HDD?
Because there are no moving parts, SSDs are essentially silent, generate far less heat, and are not as fragile as hard disk drives. But the most exciting part for computer users is the speed with which they operate.
While the fastest data transfer rate you can get from a hard disk drive is about 128 MB/s. These days, it’s not uncommon for a consumer level SSD to support a data transfer rate of well over 500 MB/s.
How does an SSD connect to my Mac Pro?
Most solid state drives on the market today connect to your system just like hard disk drives, that is, via a SATA connector. A Mac Pro has four hard drive bays, each linking up with a SATA connector on the motherboard. Sounds easy, right?
Unfortunately, there are a couple of roadblocks on our way to SSD Mac Pro nirvana. First of all, the drive bays in a Mac Pro are built to accomodate 3.5″ drives, the typical “desktop” hard disk drive most of us are familiar with. But solid state drives come in the 2.5″ form factor, or “notebook” hard drive size.
However, neither of these solutions is very satisfactory. That’s because the SATA ports in the Apple Mac Pro drive bays (and this includes the very newest Mac Pro model being sold currently) are SATA 2.0, or second generation SATA, in other words, old, slow, outdated SATA. SATA 2.0 has a theoretical limit of 300 MB/s (and a practical limit of around 275 MB/s). The current crop of SSD offerings use SATA 3,0, which supports up to 600 MB/s.
It seems a crime to purchase an SSD with a data transfer rate of 500 MB/s and plug it into a port that limits its speed to 275 MB/s.
SATA 3.0 SSD Solutions for the Mac Pro
To connect an SSD to your Mac Pro in a way that doesn’t hobble its speed, you need to bypass the hard drive bays entirely and use one of your PCI Express (PCIe) slots. In the Mac Pro universe, these are known as expansion slots. Every Mac Pro has four expansion slots on the motherboard; more than likely your graphics card is in slot 1, and you may or may not be using the other 3 slots. These slots give you much more bandwidth to play with than those measly SATA 2.0 ports.
OWC makes a line of integrated PCIe SSD cards, called Mercury Accelsior, with capacities ranging from 120 GB to 920 GB. These cards are very fast but expensive for the capacity.
My favorite solution is this SSD PCIe adapter card which allows the use of any standard SSD and supports a transfer speed of up to 550 MB/s. This is already pretty fast but you can use two of these and RAID the drives to get some truly wicked speeds. No drivers are required on the Mac, which is also nice.
PCIe 1.0 and Mac Pro 2006-2008
It should be noted that all four slots in the 2006/2007 Mac Pro, and slots 3 and 4 in the 2008 Mac Pro, use the older PCIe 1.0 standard rather than the newer PCIe 2.0. You really need a PCIe 2.0 slot to take advantage of either of the PCIe solutions I mention above. (If you don’t know which Mac Pro model you have, here is a guide.)