We've been covering the issues surrounding Samsung's SSD 840/840 Pro lately. The issue was first discovered when Anand's pre-production review sample died during testing and we also noted that in our initial review. Samsung quickly sent us another drive but it also failed after a couple of days of testing. My SSD 840 managed over a month but ironically enough, it died right after I had completed endurance testing.

Earlier Samsung told us that all review samples including our three shipped with a pre-production firmware that had a bug in it causing the failures (retail units were shipped with a newer firmware without the bug). At the time we didn't know what exactly was wrong in the firmware, but now we do. When the drive was issued a secure erase command, it would clear all table mapping information at the Address Translation Layer (ATL) but not at the Host Interface Layer (HIL). The data in both layers needs to be up-to-date for the drive operate properly, so when a write request came in, the controller wasn't able to map the data correctly, which caused the firmware to hang. An SSD obviously can't operate without a functioning firmware so from a user's standpoint, it looked like the drive had completely died even though only its firmware was broken.

All our three failures support this explanation. Our first 840 Pro sample died during a 128KB sequential write pass that we use to pre-condition our drives for enterprise tests, but the drive was secure erased just before beginning to fill the drive. The second 840 Pro died during power consumption testing but again it was secure erased right before starting the test. The regular 840 actually died when I tried to secure erase it. The secure erase command resulted in an error so I power cycled the drive but it was no longer detected by the system after reconnecting it. 

Comparison of Samsung SSD Firmware Versions
  Pre-Production Retail
Samsung SSD 840 Pro DXM02B0Q DXM03B0Q
Samsung SSD 840 DXT05B0Q DXT06B0Q

The good news is that all retail units have shipped with a newer firmware, only reviewers and others who have access to pre-production units were affected by this bug. 

For users considering the SSD 840/840 Pro, this should be reassuring news. The 840 Pro is still the fastest SATA 6Gbps SSD we have tested and it's definitely one of the top choices where performance is concerned today. The TLC NAND based SSD 840 is more mainstream focused but from what I have seen, it seems to be fairly competitively priced. The SSD 830 spoiled many with low prices but that was only to clear stocks. If you can still find a bargain SSD 830, don't hesitate to pull the trigger as those won't be available much longer, but we're more comfortable recommending the 840/840 Pro now.

While long-term reliability is still unknown, if history is any indication the 840/840 Pro are in good company as the 830 was a solid drive. Our third 840 Pro with the new fixed firmware has been going strong for weeks now and we have even recreated the scenarios that killed the earlier samples. We are also waiting for more samples from Samsung to test all capacities of SSD 840 and 840 Pro, so stay tuned!

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  • benson95 - Saturday, December 21, 2013 - link

    Hi Phil13, My 840PRO also failed a few day ago. A check also shows only 0.93GB, SN: nil and Firmware: IE'. And when you go to do the performance test on magician, it says "no volumes found on selected drive". I lost all my past 8 months worth of travel pics. Is there anyone who can help? What are the chances of recovering my data? Reply
  • Impulses - Friday, December 07, 2012 - link

    I was like "uh oh" when I read that title too... Reply
  • chedrz - Friday, December 07, 2012 - link

    I pulled the trigger on an 840 a couple weeks ago and only found out about the failing issue the day after I placed my order (by my own fault, I skimmed the article about the 840/840 Pro). I did immediately check the firmware on my drive and all is well. I haven't had any issues with my drive, and I'm glad to know Samsung is willing to disclose the exact nature of the issue for all to know. Reply
  • erple2 - Friday, December 07, 2012 - link

    So is this problem fixable by an end user (not that it should affect end users anyway)? I don't know if it's even possible to fix faulty firmware that's caused the drive to hang. Reply
  • kmmatney - Friday, December 07, 2012 - link

    The end user should be able to just update the firmware themselves (in the case that end users were affected). Most end users wouldn't do a secure-erase either.. I would sure check the firmware version if I bought one, though. I'm still using several 830s, but good to know this problem has been fixed. Reply
  • Lepton87 - Friday, December 07, 2012 - link

    So when it comes to samsung's SSDs, the best is 840pro followed by 830 and then vanilla TLC based 840? Reply
  • Impulses - Friday, December 07, 2012 - link

    830/840 trade blows depending on what you're doing, tho the 830's probably the better investment if they're both priced similarly... They're going out of stock quick tho, and were being cleared out at pretty sweet prices well before Black Friday ($0.55 - $0.65 per GB). The 840 Pro carries a huge premium right now just for being the fastest drive out there... Reply
  • HisDivineOrder - Friday, December 07, 2012 - link

    Yeah, I wish they were still selling the 830. I find the 840 to be a poor value for what they're asking, but the 840 Pro is way, way overpriced.

    The 830 hits a middle of the road in performance and price, a perfect spot really, but Samsung has thrown all that away to fleece everyone either with the crap drive at a higher price than it deserves or the great drive again at a much higher price than it deserves.

    It's a shame. They had it perfect with the 830. I wish they hadn't taken it off the market. Even before the clearing prices, it was still well below the 840 Pro's cost.
    Reply
  • Kristian Vättö - Saturday, December 08, 2012 - link

    The only reason why the 840 seems like a poor value is because the 830 sold for so cheap. If Samsung had not released the 840 series, the 830 would not have been such a bargain because Samsung would not have had a need to get rid of their 830s.

    From what I have seen by following the prices, the 840 is actually a fairly good deal compared to other SSDs. I just did a pricing table to an upcoming review a few days ago and the 840 was the cheapest of them all.
    Reply
  • Impulses - Saturday, December 08, 2012 - link

    I agree, people are being way too harsh on the 840... Even if the 830 never existed, the 840 would still be a good buy compared to similar drives like the Crucial M4, Plextor M5S, etc. Some people are just mad they missed out on deals for what was basically a clearance item, if you're pinching pennies that strongly then just wait for the next similar scenario (for instance, I'm sure there'll be an M4 replacement eventually). Reply

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