SandForce: Performance With Incompressible Data
We just highlighted the benefits of SandForce’s technology and how it's particularly effective when it comes to dealing with compressible data. However, there's another half to this story. SandForce freely admits that incompressible sequential data represents a worst case scenario for their drives. That's not a secret. The cornerstone of their DuraClass engine is based on the premise that the majority of your desktop workload consists of compressible data. While that is for the most part true, there are clear situations where your computer must deal with incompressible data, such as the scenarios listed below.
Incompressible Sequential Write Performance
All SSDs, including the ones based on SandForce's technology, exhibit the same sequential read performance when presented with incompressible information. That's good news, since most people still read more data than they write. However, the graph above highlights what SandForce's competitors are most eager to point out. That is, the m4, 830, and SSD 320 offer fairly consistent sequential write speeds, regardless of the information they operate on. SandForce-based SSDs, on the other hand, stumble when the two less common scenarios collide: writing incompressible data.
Look at the fairly small delta separating compressible data written on a 3 Gb/s configuration (the solid green line) and the incompressible numbers (both dashed lines). If you're on an older system without access to SATA 6 Gb/s connectivity, second-gen SandForce drives write incompressible data at around 240 MB/s. Upgrading to a more modern chipset for 6 Gb/s support would only yield a very small speed-up. That means you're not going to see much improvement if your workload predominately involves writing incompressible data.
On the other hand, when it comes to manipulating compressible data sequentially, the jump from 3 Gb/s to 6 Gb/s connectivity is massive. Because the majority of your desktop workload is likely better-represented by the solid bars, you really do need a 6 Gb/s-capable motherboard in order to enjoy the benefit of an SSD based on SandForce's technology.