SSD technology as a replacement for conventional hard drives has been one of the biggest advancements in modern computing, allowing for massive speed improvements along with far less power usage.
Solid-state technology has been around for years in the form of flash drives and MP3 players, but only in the past 3 to 4 years has the technology taken off, allowing for larger storage devices to be developed.
While most people envision an SSD drive to be in the form factor of a 2.5-inch notebook drive, the technology is also available in a PCI-express card format that allows for a much faster implementation for desktop systems. The PCI-express card is essentially a high-speed SCSI or SATA controller that can interface with the SSD chips much faster than current SATA implementations, and also hold far more memory chips than the 2.5-inch drive form factor. As a result, these options can implement RAID-like integration of the SSD modules that can not only increase the speed of the drive (at between 700MB/sec to 2GB/sec as opposed to 300-500MB/sec for standard SSDs), but also the security of the data on the drive by implementing redundancy.
While PCI-express based storage has been around for PC systems, so far there has been relatively little support for Macs (with FusionIO's ioDriveII and Apricon's Mac Array being only a couple of options). Even though the technology uses the same interface and drive technology that Macs use, for most PCI-express SSD options the drivers for the OS to properly interface with the controller and boot from or otherwise use it have so far only been available for Windows.
As a result of this, while you can install one of these drives in a Mac, you will likely only be able to use it if you install Windows via Boot Camp and boot directly to the Windows OS (virtual machines will not work).
While this has been the state of affairs regarding PCI-express based SSD technology, the Mac-centric upgrade and peripheral company Other World Computing has given us a sneak peek at a new PCI-express SSD card it is developing, which will be fully compatible with Mac systems. The card will use the Marvell 88SE9455 RAID controller that will interface with the SandForce 2200-based daughter cards that can be added to the main controller on demand. This will allow for user-configurable drive sizes from between 60GB and 2TB in size, allowing you to expand your storage as your need for it increases.
Unlike many other PCI-express SSD solutions, this one will be compatible with both Windows and OS X, allowing you to have greatly increased storage speeds that should work if you are booted to OS X or if you are running in Boot Camp. So far Other World Computing has only given us a sneak peek at the new drive, and does not yet offer information on the price, performance, and release date. However, in terms of price and performance we expect the drive will be exceptionally fast, but do not expect it to be cheap. Current PCI-express SSD options are exceptionally expensive, at around $1,500 for a 400-600GB option that will run at between 600-700MB/sec, compared to about $800 for the same capacity in a conventional 2.5-inch drive package, which will run at around 300-500MB/sec.
As a final thought, while people might expect this card to only be available for Mac Pro systems, Apple's Thunderbolt technology in all of its systems expands the PCI-express bus to external devices, and therefore should allow this card to be used in a number of Thunderbolt-based expansion chassis that have been developed.