Simulating a Used Drive

Since SSD performance degrades over time, it’s important to not only look at how well these drives perform new - but also the worst they’d perform over their lifetime. In order to do so we’d need a repeatable way of “seasoning” a drive to reduce its performance to the worst it could possibly get. The most realistic worst-case scenario is one where every single block on the drive is full of data. If a secure erase wipes all LBAs, that’s the best place to start. To simulate a well seasoned drive I first secure erased the drive.

After the secure erase, I used iometer to write one contiguous file across the disk - filling up the entire drive with 128KB blocks. In the case of the 80GB Intel X25-M, that’s 74.5GB of data on the drive before I run a single benchmark. The spare area is left untouched.

Next, I take my test image and I restore it onto the partition with a sector by sector copy. The sequential file write made sure that data is stored in every page of the SSD, the test image restore adds a twist of randomness (and realism) to the data.

There are other ways to produce a drive in its well-used state, but this ends up being the most consistent and repeatable. To confirm that my little simulation does indeed produce a realistically worn drive I ran PCMark on three different drives: 1) a freshly secure-erased Intel X25-M, 2) an Intel X25-M setup using the method I just described and 3) the Intel X25-M used in my CPU testbed that has been through hundreds of SYSMark runs.

The benchmark of choice is PCMark Vantage; it simulates the real world better than most drive benchmarks. The results are below:

Intel X25-M State PCMark Vantage Overall Test PCMark Vantage HDD Test
Fresh Secure Erase 11902 29879
Simulated Used Drive 11536 23252
Actual Testbed Used Drive 11140 23438

 

The secure erased system loses about 3% of its overall performance and 22% of its hard drive specific performance compared to my testbed drive. The seasoning method I described above produces a drive with nearly identical drops in performance.

The method appears to be sound.

Now that we have a way of simulating a used drive, let’s see how the contestants fared.

Restoring Your Drive to Peak Performance New vs Used SSD Performance
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  • JonasR - Friday, March 20, 2009 - link


    Thanks for an excellent article. I have one question does anyone know which controller is beeing used in the new Patriot 256GB V.3 SSD?
    Reply
  • tgwgordon - Friday, March 20, 2009 - link

    Anyone know if the Vertex Anand used had 32M or 64M cache? Reply
  • Dennis Travis - Friday, March 20, 2009 - link

    Excellent and informative article as always Anand. Thanks so much for posting the truth!! Reply
  • IsLNdbOi - Friday, March 20, 2009 - link

    Can't remember what page it was, but you showed some charts on the performance of SSDs at their lowest possible performance levels.

    At their lowest possible performance levels are they still faster than the 300GB Raptor?
    Reply
  • Edgemeal - Friday, March 20, 2009 - link

    It's too bad Windows and applications don't let you select where all the data that needs to be updated and saved to is stored. If that was an option a SSD could be used to only load data (EXE files and support files) and a HDD could be used to store files that are updated frequently, like a web browser for example, their constantly caching files, from the sound of this article that would kill the performance of a SSD in no time.

    Great article, I'll stick to HDDs for now.
    Reply
  • Luddite - Friday, March 20, 2009 - link

    So even with the TRIM command, when working with large files, say, in photoshop and saving multiple layers, the performance will stil drop off? Reply
  • proviewIT - Thursday, March 19, 2009 - link

    I bought a Vertex 120GB and it is NOT working on my Nvidia chipsets motherboard. Anyone met the same problem? I tried intel chipsets motherboard and seems ok.
    I used HDtach to test the read/write performance 4 days ago, wow, it was amazing. 160MB/s in write. But today I felt it slower and used HDtach to test again, it downs to single digit MB per second. Can I recover it or I need to return it?
    Reply
  • kmmatney - Thursday, March 19, 2009 - link

    Based on the results and price, I would say that the OCZ Vertex deserves a Editor's choice of some sort (Gold, Silver)... Reply
  • Tattered87 - Thursday, March 19, 2009 - link

    While I must admit I skipped over some of the more technical bits where SSD was explained in detail, I read the summaries and I've gotta admit this article was extremely helpful. I've been wanting to get one of these for a long time now but they've seemed too infantile in technological terms to put such a hefty investment in, until now.

    After reading about OCZ's response to you and how they've stepped it up and are willing to cut unimportant statistics in favor of lower latencies, I actually decided to purchase one myself. Figured I might as well show my appreciation to OCZ by grabbing up a 60GB SSD, not to mention it looks like it's by far the best purchase I can make SSD-wise for $200.

    Thanks for the awesome article, was a fun read, that's for sure.
    Reply
  • bsoft16384 - Thursday, March 19, 2009 - link

    Anand, I don't want to sound too negative in my comments. While I wouldn't call them unusable, there's no doubt that the random write performance of the JMicron SSDs sucks. I'm glad that you're actually running random I/O tests when so many other websites just run HDTune and call it a day.

    That X25-M for $340 is looking mighty tempting, though.
    Reply

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