Upgrade Advice: Does Your Fast SSD Really Need SATA 6Gb/s?

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

Examples include copying/creating multimedia, archive manipulation, encryption, some gameplay, and video recording

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.

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  • If you have a system that is hobbled by a lack of 6Gbs ports yet you have a good PCI spec, you can achieve 6Gbs speeds with a PCI-E card solution such as a RevoDrive. I did just that (even though my machine has 6Gbs SATA ports) as the PCI-E solution is just so simple and practical to use, and depending on which model you choose, it's speed could well exceed even what the reviewed SSDs drives can achieve.
  • The bottleneck these days is the CPU, not the port. My older processor simply can't cope with the amount of data thrown at it by my Vertex 3 240 GB - watch the CPU during an application install for example, I see the CPU maxed out.
  • All this talk of 6gBit upgrades is really annoying.
    I have a PC Express adapter in my Dell laptop that can only achieve averages of 20-30Mbytes to
    a western digital USB3 drive and a PCIe adaptor in my desktop system that randomly acheives 100MB
    for 3-4 seconds before slowng to a 35-40MB crawl for the rest of the transfer to another USB3 drive (reads or writes)

    These are claimed USB2 speeds not USB3.
    The whole thing seems to be a marketing scam for most people. My systems are quite new.
    6Gbit ? dont make me laugh.
    You need to seek out (if you can get it) very expensive upgrades to even get 30% of that speed
    in the real world.