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Benchmark Results: Random Reads And Writes

Round-Up: 15 microSDHC Cards, Benchmarked And Reviewed
By , Achim Roos

Random reads of 512 KB blocks yield the very same ranking as sequential reads. Once again, the SanDisk Mobile Ultra microSDHC is the fastest card at 21.8 MB/s.

Reducing the block size for the random read test to 4 KB significantly impacts performance, which tops out at a mere 3.4 MB/s, achieved by the Samsung and Adata Class 6 cards. There is almost no difference between queue depths of one and 32 when it comes to memory cards.

Randomly writing 512 KB blocks is not a strong suit for microSDHC cards. The three cards that perform best are the SanDisk Mobile Ultra microSDHC, the Adata microSDHC Class 6, and the Samsung card.

Benchmarking random 4 KB writes yields a rather pathetic picture, with the throughput of all but two test candidates dropping to zero-point-zero-something MB/s. In other words, that's just a few KB/s. Only the SanDisk microSDHC card and the Silicon Power card stand out with a queue depth of one. Unfortunately, that's still just over 1 MB/s.

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  • 0 Hide
    sayakbiswas , November 10, 2011 4:12 AM
    interesting read, but there should hv been more 32gb sticks.....they r quite affordable nowadays...
  • 3 Hide
    BulkZerker , November 10, 2011 5:26 AM
    sayakbiswasinteresting read, but there should hv been more 32gb sticks.....they r quite affordable nowadays...


    I wouldn't consider $40+ (shipped) affordable. Also you have to think that Tom's isn't necessarily buying these cards for personal or business use. 9x out of 10 these cards are donated by their respective companies. Or a warehouse such as Tiger Direct/Newegg.
  • 0 Hide
    CaedenV , November 10, 2011 5:50 AM
    last summer I needed some memory sticks for my video camera and decided on a pair of 16GB PNY Professional SD cards which I have been very happy with. Read maxes out my USB port, and writing is consistently above 19MB/s during file transfers.
  • 5 Hide
    Anonymous , November 10, 2011 5:53 AM
    In your test setup, I could not find a description of the interface that you use to connect these cards to the PC.
  • 0 Hide
    CaedenV , November 10, 2011 5:55 AM
    BulkZerkerI wouldn't consider $40+ (shipped) affordable. Also you have to think that Tom's isn't necessarily buying these cards for personal or business use. 9x out of 10 these cards are donated by their respective companies. Or a warehouse such as Tiger Direct/Newegg.

    $40 IS affordable for fast and dense media. You do not put fast huge SD cards in a cell phone or cheap camera, you put them in high end still cameras, and budget (but quality) video cameras. Considering when I picked mine up the nearest competition for fast SD cards were in the $80+ range, and I picked up 2 at that price I would say that $40 is quite good. If you have a cheaper camera, there is much cheaper (but still good) media out there.
  • 0 Hide
    stridervm , November 10, 2011 6:09 AM
    Would it be possible that Sandisk gave you a mislabeled Class 4 Micro SD card? Quite suspicious that they would have Class 4 cards that would perform like at least a class 6 one....
  • 1 Hide
    The_Trutherizer , November 10, 2011 6:31 AM
    I've always wondered how good these things would do in a RAID configuration. Say you got a Raid controller capable of handling 32 drives and you found a way to hook up microSD cards to it. What performance would you get? And would it be economically viable at all?
  • 2 Hide
    sayakbiswas , November 10, 2011 6:59 AM
    BulkZerkerI wouldn't consider $40+ (shipped) affordable. Also you have to think that Tom's isn't necessarily buying these cards for personal or business use. 9x out of 10 these cards are donated by their respective companies. Or a warehouse such as Tiger Direct/Newegg.



    40$ for 32gb MicroSDHC is affordable when you consider the fact that 64gb MicroSDXC cards costs 280$+. I am employing a Nikon D7000 dslr when im thinking about these cards.
  • 0 Hide
    theprov , November 10, 2011 12:06 PM
    Can i assume that a "32 gb class 10 kingston micro sd" perform at least as much as a 16 gb? I'm buying a 32 gb soon, and i don't want to find out bad surprises....
  • 1 Hide
    happyballz , November 10, 2011 12:35 PM
    Should have tested them all in one size or in two different sizes (one small one big).. performance does vary, and sometimes significantly because of design mistakes between the sizes etc.

    On a side note what is the deal with tom's being such crappy optimized webpage? I open 5-6 tabs and everything crawls to a molasses-slow on my laptop. I can open 15-20 tabs in other sites no problem.

  • 0 Hide
    bfstev , November 10, 2011 12:36 PM
    so where can anyone get the memory star models? I cant find them anywhere
  • 2 Hide
    Anonymous , November 10, 2011 1:57 PM
    @stridervm

    actually sandisk are exceptional cards, from past experience i have found that sandisk consistently have better performance and compatibility than many other brands. The class 4 could just be a lower binned class 10, which means not all class 4 will have this kind of performance (but will meet class 4)

    @The_Trutherizer

    I have often thought about such a setup too but i think the hardware and controllers required to transverse such a setup would probably not make it economically viable, still someone should do it just to say you can lol

    @theprov

    generally speaking no, but what you can deduce from this article is that if it's labeled class 10, then it will guarantee to meet the minimum performance of a class 10 (although i have to say i used some no name cards before labeled as class 10 but barely beat a class 4, but kingston is a good brand and should easily meet class 10 specs), if you really need better speeds then class 10 than you need to look towards the newer UHS (U1 and U2) speeds, but bear in mind their are precious few hardware that can utilize such speeds and the cards are ridiculously expensive. From my past experience i have found kingston to be on par with sandisk when it comes to performance and compatibility so i dont think your going find any bad surprises
  • 1 Hide
    bounty , November 10, 2011 4:03 PM
    Nice article. I would have liked to have seen a price/performance chart for each capacity. Possibly price/capacity chart. Looks like the Adata and Patriot at 16Gb are good deals.
  • 2 Hide
    Anonymous , November 10, 2011 4:04 PM
    You should have tested these cards inside a mobile device, such as the Galaxy SII, because write/read speeds would be different. I personally do not care about these results because they do not reflect the real usage. Since the SII is a popular device, those results would matter, and not these. I don't know anybody that would buy a microsdhc and use it in a PC.

    And secondly, you do not ask the producers for a sample card. They will send you the best of their cards. Instead, you should buy them as a regular buyer. You know what I mean.
  • 2 Hide
    pc000007 , November 10, 2011 9:21 PM
    The Kingston 8GB in the test didn't meet Class10 specification, which is write speed of at least 10MB/s. The 4GB just scraped in.

    Also I have found that IO results differ wildly depending on what card reader is used. I don't understand how but I have seen cards perform at 25% the speed just by benchmarking using a different card reader.
    Any testing been done by Toms in this area?
  • 1 Hide
    insz , November 10, 2011 9:42 PM
    Can anyone shed more light on why the 4k random write tests are so slow, and why the Sandisk class 4 card does so well in that?

    It's a common problem for people who run Android on their B&N Nook Color off of an SD card, as small random reads and writes are most of what the OS does, and the difference in performance between a class 4 Sandisk and any class 10 card is night and day.
  • 2 Hide
    martel80 , November 11, 2011 7:49 AM
    I think testing at QD > 1 makes no sense for memory cards (and their typical usage).
  • 0 Hide
    WyomingKnott , November 11, 2011 6:01 PM
    Haven't even read it yet but: Thank you, thank you, thank you!
  • -3 Hide
    Anonymous , November 12, 2011 1:19 PM
    Who cares about sustained transfer rates? What are the Random 4K reads/writes? These cards are being used in tablets and in Windows 7 PCs for readyboost, and sustained transfer speeds mean nothing.
  • -2 Hide
    jemm , November 14, 2011 10:44 AM
    Great article for reference.
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