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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  • Kristian Vättö - Sunday, December 09, 2012 - link

    What chipset do you have? Or better yet, what exact motherboard? The more specs I have, the easier it is for me to inform Samsung. I don't have two 840/840 Pros at the moment so I can't try to recreate the issue, but I'll definitely drop them a note once I have the specs I need. Reply
  • Brahmzy - Sunday, December 09, 2012 - link

    Hi Kristian, thanks for the quick response.
    System is an ASUS P8P67 Deluxe B3, BIOS 3509 (modded OROM 11.6.x.x for TRIM, which works fabulously, btw). 128k stripe. I will note I swapped cables and even switched both drives to 2 spare intel SATA2 ports - still would not post until I unplugged one of the drives. Once I broke the array, system posted fine with both drives plugged in. As stated earlier, I was able to recreate the array and load up an OS.
    Reply
  • Kristian Vättö - Monday, December 10, 2012 - link

    Brahmzy,

    Can you email me at kristian@anandtech.com? I contacted Samsung and they are looking into the issue but would like your contact information for possible further questions about your issue/setup.
    Reply
  • Brahmzy - Thursday, December 13, 2012 - link

    Email sent - sorry about the delay. My newly built array is still running fine after the rebuild, so we'll see. Curious about the new firmware! Reply
  • crimson117 - Monday, December 10, 2012 - link

    Did you update the benchmarks using the consumer firmware?

    Curious whether the fix compromises performance at all.
    Reply
  • fronzel - Wednesday, December 12, 2012 - link

    You guys should put two drives like the 840s in RAID0 on a z77 board and run it through your storage bench! It seems like a popular setup, and i'm considering it myself. TRIM should work okay with the new drivers, but i'm curious how it scales and if there are any quirks or drawbacks with on-board raid with these SSD drives. Reply
  • Tommyv2 - Friday, December 14, 2012 - link

    There's a new firmware for the 840 Pro at least... just came out today! Reply
  • CDJay - Thursday, December 27, 2012 - link

    I got a 512gb 840 Pro a few weeks back. I performed the latest firmware upgrade just over a week ago.

    Two days ago, the drive wasn't detected when the PC was turned on. As it's a drive dedicated to Steam, it wasn't too catastrophic, fixed with a simple power cycle.

    Same again today, except I can't resurrect it. I've swapped all cables, tried a different controller, moved over to another PC and done the same there. It is, officially, dead.

    I'll get it returned, but I'm fairly happy it's my Steam drive (which I'd backed up to NAS when I installed the drive) as I can recover easily. However, I was testing the drive with a view to using as an O/s drive as well, not to mention rolling out in my fiancées studio PC and other PCs I'll build for people going forward. This gives me pause, unsurprisingly!
    Reply
  • longtom - Sunday, December 30, 2012 - link

    The new firmware (DXM04B0Q) causes the 840 Pro to read/write at half speed on the AMD SB950 chipset.

    I get 250MB/s and 230MB/s Write.

    I find it fishy that this firmware is release 4, yet the Samsung Website states that it is 1.0.

    I am done with this junk. I will call tomorrow for the 6th time and demand a full refund.

    I will instead buy Intel's new drives.
    Reply
  • ZipTang - Friday, January 04, 2013 - link

    My first 840 Pro started disappearing randomly, often long after the computer had been booted. Rebooting usually brought it back.

    Then it didn't. CheckDisk ran, and when it was done, half my files were gone. (But backed up, so I didn't freak.)

    Samsung swapped it for a drive with DXM04B0Q firmware on December 17.

    That drive is starting to go. It started disappearing. CheckDisk just ran. No files seem to be missing, but this is beyond frustrating. Do I swap it for another? Is there any hope that another one will be better, or is there something bigger wrong? The two 830 drives in the same machine seem fine. Got them on sale when the 840 pro was being released.
    Reply

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