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


View All Comments

  • Kary - Thursday, March 19, 2009 - link

    The extra space would be invisible to the end user (it is used internally)

    Also, addressing is normally done in a result actual sizes are typically in binary in memory devices (flash, RAM...):

    80 GB...not compatible with binary addressing

    (though 48GB of a 128GB drive being used for this seems pretty high)
  • ssj4Gogeta - Wednesday, March 18, 2009 - link

    Did you bother reading the article? He pointed out that you can get any SSD (NOT just Intel's) stuck into a situation when only a secure erase will help you out. The problem is not specific to Intel's SSD, and it doesn't occur during normal usage. Reply
  • MarcHFR - Wednesday, March 18, 2009 - link

    The problem i've pointed out has nothing to do with the performance dregradation related to the write on a filled page, it's a performance degradation related to an LBA optimisation that is specific to Intel SSD.
  • VaultDweller - Wednesday, March 18, 2009 - link

    So where would Corsair's SSD fit into this mix? It uses a Samsung MLC controller... so would it be comparable to the OCZ Summit? I would expect not since the rated sequential speeds on the Corsair are tremendously lower than the Summit, but the Summit is the closest match in terms of the internals. Reply
  • kensiko - Wednesday, March 18, 2009 - link

    No, OCZ Summit = newest Samsung controller. The Corsair use the previous controller, smaller performance. Reply
  • VaultDweller - Wednesday, March 18, 2009 - link

    So what's the difference?

    The Summit is optimized for sequential performance at the cost of random I/O, as per the article. That is clearly not the case with the Corsair drive, so how does the Corsair hold up in terms of random I/O? That's what I'm interested in, since the sequential on the Corsair is "fast enough" if the random write performance is good.
  • jatypc - Wednesday, March 18, 2009 - link

    A detailed description of how SSDs operate makes me wonder: Imagene hypothetically I have a SSD drive that is filled from more than 90% (e.g., 95%) and those 90% are read-only things (or almost read-only things such as exe and other application files). The remaining 10% is free or frequently written to (e.g., page/swap file). Then the use of drive results - from what I understood in the article - in very fast aging of those 10% of the SSD disk because the 90% are occupied by read-only stuff. If the disk in question has for instance 32GB, those 10% are 3.2 GB (e.g., a size of a usual swap file) and after writing it approx. 10000 times, the respective part of the disk would become dead. Being occupies by a swap file, this number of reads/writes can be achieved in one or two years... Am I right? Reply
  • sbuckler - Wednesday, March 18, 2009 - link

    Depends on how smart the controller is? Shuffling around the data now and again in the background would make sense. Reply
  • Frallan - Wednesday, March 18, 2009 - link

    This is why i come to AT to read up on the developments.

    Well played :0)

    The ruler of the roost are the Intels however I will be able to afford one of those when there are cows enjoying themselfs by dancing on the moon. My next upgrade will be a Vertex - not only bc its Valu for money but equally much bc. OCZ obviously takes care of thier customers and listens to reason.
  • pmonti80 - Wednesday, March 18, 2009 - link

    This is the kind of article that makes me come back here. Reply

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