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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  • niva - Friday, December 7, 2012 - link

    Logged in expecting some real damage to Samsung and instead this was a positive article. Maybe you should consider revising the title to something less negative.
  • Iketh - Friday, December 7, 2012 - link

    I was quite relieved since I've owned the 840 since release... No problems here BTW, been flawless.
  • SlyNine - Friday, December 7, 2012 - link

    Yes, they need to change the title. Not everyone takes the time to actually read through articles. Someone might just see the headline and stay away from, what is an otherwise good SSD.
  • Kristian Vättö - Friday, December 7, 2012 - link

    Better now?
  • SlyNine - Friday, December 7, 2012 - link

    Much, thank you.
  • jmke - Monday, December 10, 2012 - link

    change title indeed :)

    "Samsung Explains The Pre-Release Firmware Bug Causing The Failures of SSD 840/840 Pro"
  • just4U - Saturday, January 5, 2013 - link

    I like the old title better.. CHANGE IT BACK!!! err... what was the old title anyway? :/
  • phil13 - Wednesday, December 11, 2013 - link

    I have one that failed, only show 0.9GB, SN: 000000000, Firmware: DXT06BO0, even samsung Magician software can see it, but say that there is no samsung SSD drive.
  • phil13 - Wednesday, December 11, 2013 - link

    It does look the firmware problem, all feel ok.
  • phil13 - Wednesday, December 11, 2013 - link

    Any solution? appreciate, thanks.

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