A week ago Samsung acknowledged the existence of the read performance bug in the SSD 840 EVO and I just received a note that the fixed firmware is in validation process and is expected to be released to the public on October 15th. Unfortunately I don't have any further details about the bug or the fix at this point, or whether the update is coming to the 'vanilla' SSD 840 and OEM models, but I hope to get more details as the public release gets closer, so stay tuned.

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  • ThisWasATriumph - Friday, September 26, 2014 - link

    In the meantime, DiskFresh can read and write each sector once, which will temporarily fix performance issues. I used it on the first 40% of my drive and its back to full speed. http://download.cnet.com/DiskFresh/3000-18512_4-75...
  • Maltz - Friday, September 26, 2014 - link

    I've wondered about booting my MacBook Pro into single-user mode and doing a dd if=/dev/rdisk0 of=/dev/rdisk0 bs=1m. Seems like that should work, but it would put a lot of wear on the drive. If it's only about three weeks away, I think I might just wait for the firmware update.
  • dylan522p - Friday, September 26, 2014 - link

    The firmware update is pretty much just gonna be aggressively moving data around so that it never gets old and the voltages in the cells do not drop.
  • boozed - Friday, September 26, 2014 - link

    How sure of this are you?
  • Maltz - Friday, September 26, 2014 - link

    There was one school of thought that speculated that the problem was fading charges in the TLC NAND, but given the complete lack of data loss, I personally find that unlikely.

    Another theory was that the wear-leveling routines were moving data around in such a way that eliminated the parallelism between NAND modules, thus slowing down the drive. If this is the case, the re-arranging of data to speed things back up would be a one-time event, but would still have to occur.

    But, it's all just speculation at this point, of course.
  • hojnikb - Saturday, September 27, 2014 - link

    Well, thats a pretty bad theory. Even if data was moved around in such manner, it would still be faster than 50MB/s (or even less in some cases). ToggleDDR is good for ~400MB/s, so even if data is on a single package for some reason, it still woulnd hit performance so hard.
  • Solid State Brain - Friday, September 26, 2014 - link

    Putting aside controller strategies (read: ECC) that on normally functioning drives are probably occurring to ensure that read operations remain reliable with wear and usage, if static data has the chance to become old with normal usage patterns it likely means that the controller wasn't moving it around at all. Every time the SSD's wear leveling count increases by one, all NAND flash cells are supposed to have been written on once on average and this is going to happen at least once a month with just 4-5 GB of daily host writes on a 250GB drive on average, assuming a write amplification of 2, which would represent a very light usage.

    So it's not a matter of "aggressively moving data around", but to actually get it to move around in the first place, assuming the bug isn't affecting something else instead (like for example the metadata associated with the recorded data as it gets shuffled around).
  • chrysrobyn - Monday, September 29, 2014 - link

    How about dd if=/dev/rdisk0 of=/dev/null bs=1m? DD will read all the sectors, but it won't put them anywhere, so no write wearing.
  • Mugur - Saturday, September 27, 2014 - link

    Hopefully they will release a fix for the old 840 too... I have 4 of these at work and I was just going to make a big storage spaces pool with 2 layers out of them. Not sure that the bug will show in this context, but if there will be some static most accesed files moved to ssd by storage spaces I assume yes.
  • Death666Angel - Saturday, September 27, 2014 - link

    I have a 840 500GB as my system and steam drive here. Haven't noticed any slow downs at any point during the last 18 months I had it. Benchmarks during that time always showed it operating a few 10s of MB below peak performance for my SATA II (old P55 chipset) and now SATA II (Z87) connections.

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