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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  • hellcats - Saturday, March 21, 2009 - link

    Anand,

    What a great article. I usually have to skip forwards when things bog down, but they never did with this long, but very informative article. Your focus on what matters to users is why I always check anandtech first thing every morning.
    Reply
  • juraj - Saturday, March 21, 2009 - link

    I'm curious what capacity is the OCZ Vertex drive reviewed. Is it an 120 / 250g drive or supposedly slower 30 / 60g one? Reply
  • Symbolics - Friday, March 20, 2009 - link

    The method for generating "used" drives is flawed. For creating a true used drive, the spare blocks must be filled as well. Since this was not done, the results are biased towards the Intel drives with their generous amount of spare blocks that were *not* exhausted when producing the used state. An additional bias is introduced by the reduction of the IOmeter write test to 8 GB only. Perhaps there are enough spare blocks on the Intel drives so that these 8 GB can be written to "fresh" blocks without the need for (time-consuming) erase operations.
    Apart from these concerns, I enjoyed reading the article.
    Reply
  • unknownError - Saturday, March 21, 2009 - link

    I also just created an account to post, very nice article!
    Lots of good well thought out information, I'm so tired of synthetic benchmarks glad someone goes through the trouble to bench these things right (and appears to have the education to really understand them). Whats with the grammar police though? geez...
    Reply
  • Erickffd - Friday, March 20, 2009 - link

    Also created an account just to post this comment.

    Really impressive and well done article ! Will stay tune for further developments and reviews. Thank you so much :)

    Also... very impressed by OCZ's respond and commitment upon end users needs and product quality assurance (unfortunately not so commun by large this days among other companies). Certanly will buy from them my next SSDs to reward and support their healty policy.

    Be well ! ;)
    Reply
  • Gasaraki88 - Friday, March 20, 2009 - link

    This truly was a GREAT article. I enjoyed reading it and was very informative. Thank you so much. That's why Anandtech is the best site out there. Reply
  • davidlants - Friday, March 20, 2009 - link

    This is one of the best tech articles I have ever read, I created an account just to post this comment. I've been a fan of Anandtech for years and articles like this (and the RV700 article from a while back) show the truly unique perspective and access that Anand has that simply no other tech site can match. GREAT WORK!!! Reply
  • Zak - Friday, March 20, 2009 - link

    I just got the Apex. I'd probably cough up more dough for the Vertex after reading this. However, I've run it for two days as my system disk in MacPro and haven't noticed any issues, it's really fast. But I guess I'll get Vertex for my Windows 7 build.

    Z.
    Reply
  • Nemokrad - Friday, March 20, 2009 - link

    What I find intriguing about this article is that these smaller manufacturers do not do real world internal testing for these things. They should not need 3rd parties like you to figure this shit out for them. Maybe now OCZ will learn what they need to do for the future. Reply
  • 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

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