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Samsung's 840 EVO update fixes slow reads with old data

  1. #1


    USA
    Posts : 689
    Windows 8.1 Pro with Media Center

    Samsung's 840 EVO update fixes slow reads with old data


    Not sure where the appreciate place for this should be but...

    It seems the Samsung 840 EVO had a long undiscovered issue which was finally addressed this week

    Last month, Samsung confirmed that its 840 EVO SSD can suffer from slower read speeds with older data. The company promised to address the issue with updated firmware, and we've been experimenting with the fix.

    Before we get into the results of our testing, we should spend a moment on the problem itself. Here's how Samsung describes the issue:

    SSDs usually calibrate changes in the statuses of cells over time via the flash management software algorithm. Due to the error in the software algorithm, the 840 EVO performed read-retry processes aggressively, resulting in a drop in overall read performance. This only occurs if the data was kept in its initial cell without changing, and there are no symptoms of reduced read performance if the data was subsequently migrated from those cells or overwritten.

    Read-retry is used to compensate for changes in cell voltages, suggesting that voltage drift over time was a key factor here. The EVO's flash management routines evidently haven't been responding to voltage changes correctly.

    Fixing the problem is a two-part process managed by Samsung's appropriately named Performance Restoration tool. First, the utility flashes the SSD's firmware with the new EXT0CB6Q revision. Then, it reboots the system and completes the restoration process, which we're told involves "conditioning" the NAND. The entire process is non-destructive, so it shouldn't compromise any data on the drive. It also only needs to be run once. That said, the target drive must have at least 10% free capacity for the tool to work its magic.

    The data on the 840 EVOs we have in the lab isn't old enough to be affected by the flaw. Fortunately, our resident developer, Bruno "morphine" Ferreira, has been running an 840 EVO 500GB in his personal system for more than 10 months. Having already noticed slower performance with older files, he bravely volunteered to test Samsung's fix.

    The restoration process went off without a hitch, though it took over an hour to condition Bruno's drive. Read speeds seem to be much improved. Below is a screenshot from HD Tach, which tests read performance across the extent of the drive. Click the buttons below the image to switch between results from before and after the fix was applied.
    Source: Samsung's 840 EVO update fixes slow reads with old data - The Tech Report - Page 1

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  2. #2


    India
    Posts : 1,536
    Win 8.1 Update x64


    So that's the latest Samsung 840 Evo SSD firmware update , lot of thanks for posting this

    Seems the Performance restoration tool is released by Samsung.

    Also, I could read this:
    " Given how the bug manifests, we won't know if the EVO is truly fixed until at least a month from now, when freshly written data will be old enough to exhibit slower read performance. Samsung is confident that the problem has been addressed, though, and the company has updated its validation procedures to look for similar issues in future products. For what it's worth, Samsung says the problem is unique to the 840 EVO and not an artifact of that drive's TLC NAND. The older, TLC-based 840 Series is unaffected, and so is the upcoming 850 EVO, which will use the three-bit version of 3D V-NAND.

    There are still some associated caveats, like the updater not working with SSDs in RAID arrays or with older AMD SATA drivers, but those restrictions aren't too different than those that typically come along with new SSD firmware."

    Should I wait for 1 month for reviews & feedbacks on the latest firmware benefits, and then proceed with the firmware update in my system?
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  3. #3


    USA
    Posts : 689
    Windows 8.1 Pro with Media Center


    I really don't have an answer for you. Also from what I understand this only affects the EVO's. I've got an 840 and 850 Pro and none of them are affected.

    Anyway I'm I'm surprised this hasn't been mentioned here or in seven forums, thus my posts here and there. As a photographer I'm also registered over at DP Review which is where I fist read about it. They have a thread going on about it here - Samsung 840 EVO users 'heads-up' re performance issue/bug...

    Other than that all I can say is if you have an 840 EVO, update and wait and see.
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  4. #4


    India
    Posts : 1,536
    Win 8.1 Update x64


    Okay, I'm in.

    This would be just like our OEM laptop firmware update for BIOS/UEFI etc. isn't it? Just to confirm.

    This is my first time doing this & this is my first SSD, so you could guess that I don't know a thing about this

    I too was surprised no one had put this topic anywhere else eventhough a bunch of us here have Samsung Evo SSD . Anyway no worries, you've put it, right

    EDIT: Firmware updated to latest.

    Read improvement is noticeable in Samasung Magician performance benchmark (RAPID mode is disabled):

    Navy blue: after firmware update
    Light blue: before firmware update

    Click image for larger version
    Last edited by visruth; 19 Oct 2014 at 02:07. Reason: 840 Evo Firmware Updated
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  5. #5


    USA
    Posts : 689
    Windows 8.1 Pro with Media Center


    Looking at now, perhaps I should have put this in the Performance & Maintenance section where it would have gotten more traction. Anyway SSD performance and/or issues isn't my strong suit. Perhaps someone in this thread would be more helpful to your questions. I just posted this here as news.

    The one in the seven forums is a little more active though as I posted my benchmarks for both my 840 and 850 Pro.

    BTW remember the bug only affected files of a certain age, so unless you're looking at those files you may not notice a performance degradation. Point is even in updating the firmware you may not readily know if the issue is fixed unless you look at your old files. This is why it took Samsung so long to discover it. Again, if you read through the thread over at DP Review and read Jim Cockfield's posts he does a good job of explaining what's happening
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  6. #6


    India
    Posts : 1,536
    Win 8.1 Update x64


    Guess I've to wait for few months to notice the difference in performance.

    Yes it's explained very good in those articles and forums, thanks for that
      My System SpecsSystem Spec

  7. #7


    Posts : 3
    8.1 Pro


    Quote Originally Posted by visruth View Post
    So that's the latest Samsung 840 Evo SSD firmware update , lot of thanks for posting this

    Seems the Performance restoration tool is released by Samsung.

    Also, I could read this:
    " Given how the bug manifests, we won't know if the EVO is truly fixed until at least a month from now, when freshly written data will be old enough to exhibit slower read performance. Samsung is confident that the problem has been addressed, though, and the company has updated its validation procedures to look for similar issues in future products. For what it's worth, Samsung says the problem is unique to the 840 EVO and not an artifact of that drive's TLC NAND. The older, TLC-based 840 Series is unaffected, and so is the upcoming 850 EVO, which will use the three-bit version of 3D V-NAND.

    There are still some associated caveats, like the updater not working with SSDs in RAID arrays or with older AMD SATA drivers, but those restrictions aren't too different than those that typically come along with new SSD firmware."

    Should I wait for 1 month for reviews & feedbacks on the latest firmware benefits, and then proceed with the firmware update in my system?

    I have two 840 EVOs in a RAID array as my boot disk. I am definitely seeing a performance reduction. I guess I am out of luck because this updater does not work for RAID arrays.
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  8. #8


    India
    Posts : 1,536
    Win 8.1 Update x64


    Yes, that's what they say. May be they would come with algorithms for RAID too in the future.
      My System SpecsSystem Spec

  9. #9


    Posts : 3
    8.1 Pro


    My SSD RAID is still faster than a single SSD would be, so I think I will wait for now.
      My System SpecsSystem Spec

  10. #10


    India
    Posts : 1,536
    Win 8.1 Update x64


    Glad that Samsung is actually conducting R&D on all its flagship SSD models for its improvement and identifying the faults persisting.
      My System SpecsSystem Spec

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Samsung's 840 EVO update fixes slow reads with old data
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