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

Real-World Tests

After receiving a number of requests for more real-world testing, we're moving in that direction. Our trace-based benchmarking gives you a holistic performance picture. And the more specific random/sequential read/write measurements drill down into more targeted workload profiles.

However, we still haven't answered our original question in a way that makes the decision to use your new SSD on an old platform or buy something new any easier. Does our testing indicate the need for 6 Gb/s connectivity or not?

We know that most of our real-world tests see queue depths of one, and involve a mixture of compressible and incompressible data. In this particular test, we're transferring 11 GiB worth of video clips (which, of course, you can't really smash down any more than the H.264 compression standard), along with a slew of smaller files that are compressible.

Here's where things get interesting. Because of this workload's profile, there's frankly very little improvement to realize in jumping from SATA 3Gb/s to SATA 6Gb/s. Crucial's m4, for example, performs exactly the same at both data rates.

Yes, the Samsung and OCZ drives are able to present quantifiable gains. However, the real story here is a comparison to even the slowest SSD, Intel's SSD 320, and Western Digital's Scorpio Blue, a drive you might have installed in a notebook. The reality of the situation is that this battle isn't between the fastest and slowest SSDs, it's a matter of comparing hard drives to solid-state storage.

Backing up a game using Steam incorporates a mix of incompressible and compressible sequential writes, along with a sizable number of random write operations. This task also involves a good deal of host processing as individual files are packed into archives. The result is that there's not much difference between SATA 3Gb/s and 6Gb/s, or even between the SSDs and hard drive, since storage surprisingly isn't a big bottleneck.

Of course, we know that storage performance is only one determinant of benchmark results. Remember our office productivity analysis? In nearly 30 minutes of antivirus scanning, our SSD was only busy for 281 seconds. In essence, the task wasn't taxing enough to demonstrate an SSD's benefit.

In order to push the test harder, you have to add concurrent operations. For example, we can still transfer files to and from the SSDs while the backup operation executes with minimal penalty. On a hard drive, however, the same multi-tasked workload slows both actions to a crawl.

Measuring boot time is one of the best examples of how an SSD excels. You get a mix of random and sequential reads, along with some write operations attributable to logging. Queue depths during Windows boot can easily exceed four, as the operating system accesses multiple files in quick succession or at the same time.

The differences between the SSDs are again very minor, while the hard drive drags. Don't expect SATA 6Gb/s to buy you any additional speed in this metric, though.

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  • dizzy_davidh
    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.
  • outbackkid
    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.
  • Anonymous
    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.