New vs Used SSD Performance

We begin our look at how the overhead of managing pages impacts SSD performance with iometer. The table below shows iometer random write performance; there are two rows for each drive, one for “new” performance after a secure erase and one for “used” performance after the drive has been well used.

4KB Random Write Speed New "Used"
Intel X25-E   31.7 MB/s
Intel X25-M 39.3 MB/s 23.1 MB/s
JMicron JMF602B MLC 0.02 MB/s 0.02 MB/s
JMicron JMF602Bx2 MLC 0.03 MB/s 0.03 MB/s
OCZ Summit 12.8 MB/s 0.77 MB/s
OCZ Vertex 8.2 MB/s 2.41 MB/s
Samsung SLC 2.61 MB/s 0.53 MB/s
Seagate Momentus 5400.6 0.81 MB/s -
Western Digital Caviar SE16 1.26 MB/s -
Western Digital VelociRaptor 1.63 MB/s -

 

Note that the “used” performance should be the slowest you’ll ever see the drive get. In theory, all of the pages are filled with some sort of data at this point.

All of the drives, with the exception of the JMicron based SSDs went down in performance in the “used” state. And the only reason the JMicron drive didn’t get any slower was because it is already bottlenecked elsewhere; you can’t get much slower than 0.03MB/s in this test.

These are pretty serious performance drops; the OCZ Vertex runs at nearly 1/4 the speed after it’s been used and Intel’s X25-M can only crunch through about 60% the IOs per second that it did when brand new.

So are SSDs doomed? Is performance going to tank over time and make these things worthless?


"Used" SSD performance vs. conventional hard drives.

Pay close attention to the average write latency in the graph above. While Intel’s X25-M pulls an extremely fast sub-0.3ms write latency normally, it levels off at 0.51ms in its used mode. The OCZ Vertex manages a 1.43ms new and 4.86ms used. There’s additional overhead for every write but a well designed SSD will still manage extremely low write latencies. To put things in perspective, look at these drives at their worst compared to Western Digital’s VelociRaptor.The degraded performance X25-M still completes write requests in around 1/8 the time of the VelociRaptor. Transfer speeds are still 8x higher as well.

Note that not all SSDs see their performance drop gracefully. The two Samsung based drives perform more like hard drives here, but I'll explain that tradeoff much later in this article.

How does this all translate into real world performance? I ran PCMark Vantage on the new and used Intel drive to see how performance changed.

PCMark Overall Score New "Used" % Drop
Intel X25-M 11902 11536 3%
OCZ Summit 10972 9916 9.6%
OCZ Vertex 11253 9836 14.4%
Samsung SLC 10143 9118 10.1%
Seagate Momentus 5400.6 6817 - -
Western Digital VelociRaptor 7500 - -

 

The real world performance hit varies from 0 - 14% depending on the drive. While the drives are still faster than a regular hard drive, performance does drop in the real world by a noticeable amount. The trim command would keep the drive’s performance closer to its peak for longer, but it would not have prevented this from happening.

PCMark Vantage HDD Test New "Used" % Drop
Intel X25-M 29879 23252 22%
JMicron JMF602Bx2 MLC 11613 11283 3%
OCZ Summit 25754 16624 36%
OCZ Vertex 20753 17854 14%
Samsung SLC 17406 12392 29%
Seagate Momentus 5400.6 3525 -  
Western Digital VelociRaptor 6313 -  

 

HDD specific tests show much more severe drops, ranging from 20 - 40% depending on the drive. Despite the performance drop, these drives are still much faster than even the fastest hard drives.

Simulating a Used Drive SSD Aging: Read Speed is Largely Unaffected
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  • siberx - Thursday, March 19, 2009 - link

    This is, very likely, the best article I have ever read, period. Online, in magazines, about any subject... this was an absolutely fantastic read. Suddenly, all smoke surrounding SSDs has cleared and the truth shines through in editorial brilliance. It's great to see that at least some computer news sites out there can still cut through the crap and get to the heart of the issue. My already high opinion of AnandTech has risen even further.

    Thank you for taking the immense time it must have taken to compile and assemble all this information - this article is now a must-read for *anybody* considering purchasing an SSD, and it's just about all the background you could need in one place.

    In addition to all the extremely useful general SSD information contained within, the detailing of the issues with the JMicron controllers as well as OCZ's efforts to address the concerns to produce the best product possible (despite the reduced marketability to the uninformed) is reassuring and comforting in a world where tech companies seem more concerned with how much they can deceive their customers instead of producing quality products.

    In short, the article is a win on all fronts, thank you greatly for posting it. When I purchase my first SSD (which I'm considering doing reasonably soon) this article, its information and suggestions, and OCZs actions to resolve the issues with its drives will definitely be at the forefront of my mind.
    Reply
  • jkua - Thursday, March 19, 2009 - link

    I have to say, I really appreciate the effort and throughness with which you have covered the state of the SSD market today. As an engineer and scientist, I applaud your methods in tracking down and reporting the major issues with SSDs. As a consumer, I really appreciate the timeliness of this article as I was just thinking of putting an SSD in a netbook for a robotics application where mechanical drives are not ideal.

    Cheers!
    Reply
  • jkua - Thursday, March 19, 2009 - link

    That said, one thing I would have like to have seen is some numbers on power consumption for these drives compared to average mechanical desktop and laptop drives. Reply
  • aamsel - Thursday, March 19, 2009 - link

    Anyone have a link to the Intel HDD ERASE program that Anand referred to? Reply
  • HolyFire - Thursday, March 19, 2009 - link

    http://www.ultimatebootcd.com/download.html">http://www.ultimatebootcd.com/download.html (includes HDD erase 3.1)

    http://cmrr.ucsd.edu/people/Hughes/SecureErase.sht...">http://cmrr.ucsd.edu/people/Hughes/SecureErase.sht... (version 4.0)
    Reply
  • AnnonymousCoward - Thursday, March 19, 2009 - link

    AWESOME ARTICLE.

    The huge difference in read/write flash performance looks a lot like this article: http://www.anandtech.com/memory/showdoc.aspx?i=257...">http://www.anandtech.com/memory/showdoc.aspx?i=257...
    Reply
  • wind glider - Thursday, March 19, 2009 - link

    Thanks for the orgasmic review. Reply
  • wicko - Wednesday, March 18, 2009 - link

    Had a really good read here, thanks for the history and info, Anand. The only thing I don't understand is what the importance of random write is? What kind of task would benefit from high random write speeds (maybe copying many files at once)? I'm tempted to pick up a vertex drive but it depends on whether or not random write will be important for me. But the price... whoa, pretty damn expensive here in Canada.. http://www.ncix.com/products/index.php?sku=36023&a...">http://www.ncix.com/products/index.php?...X120G&am... - $625 for a 120GB!!! I kind of want 2, for RAID0, I have a lot of games installed (steam folder alone is 100GB lol). Might even have to raid 3 of em.. but not for $1800 lol. Reply
  • strikeback03 - Thursday, March 19, 2009 - link

    As mentioned in the article, the OS in general makes lots of random writes. Send an IM, it writes to a log. Load a website, it caches some images. Reply
  • AnnonymousCoward - Thursday, March 19, 2009 - link

    >I'm tempted to pick up a vertex drive but it depends on
    >whether or not random write will be important for me.
    Keep in mind, its random write is twice as fast as mechanical HDs.

    >But the price...
    It's only $110USD/32GB.
    Reply

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