Samsung Explains The Firmware Bug Causing The Failures of SSD 840/840 Pro

by Kristian Vättö on December 7, 2012 1:05 PM EST

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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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Impulses - Saturday, December 08, 2012 - link
That's kind of a cynical point of view, though a valid one I guess, I'm sure Anandtech will re-run tests on a different capacity 840/840 Pro at some point though. The bug, as explained in this news article, wouldn't really affect performance, so it doesn't support your theory...

I'd say the better question would be whether they discovered this bug on their own and fixed it before drives shipped out, or whether they were only made aware of it once Anand/Kristian and others reported drive failures w/the review samples...

If it's the former, I'd say that speaks highly of Samsung's validation (they were testing it even after review samples were sent out), if it's the latter then I guess it's a bit of black eye on their part but they still deserve credit for a really quick turnaround on the fix. Reply
Henk Poley - Saturday, December 08, 2012 - link
That's why even for a tiny embedded system inside a harddisk, it's smarter to put the boot disk on another storage device. Reply
Azethoth - Monday, December 10, 2012 - link
Huh what? How does doubling the number of storage systems used lead to a smaller failure rate? Reply
longtom - Saturday, December 08, 2012 - link
I just created an account to say that they haven't fixed it yet.

I bought two of these last week (both with the newest firmware - verified) to test under RAID0 for benchmarking and as far as BIOS or Windows is concerned, they don't exist at all when paired in RAID on the AMD SB950 (with newest BIOS firmware).

I know this is a problem with the 840 because, to confirm my suspicions, I pulled several SSDs out of my pile to put on RAID, and they all worked flawlessly.

I am still very disgruntled with this product. "Buyer Beware" until they come out with yet another firmware revision. Reply
frief - Saturday, December 08, 2012 - link
Hi longtom,

did you do a secure erase at some time? (I'm a little shy as I've been burnt by Indilinx, Crucial M4 and Seagate Momentus and if I don't learn from that when will I ever learn?) Reply
Kristian Vättö - Saturday, December 08, 2012 - link
Is the problem just when you're RAIDing them (i.e. do they show up normally when not in RAID)? Reply
longtom - Sunday, December 09, 2012 - link
Both of these drives did not work straight out of the packaging. Yes, they only do not work when in a RAID. When out of RAID they work fine. However, when in any form of RAID configuration on the AMD SB950 Southbridge (990FX, a popular chip right now) the drive is INVISIBLE to both BIOS and Windows, even after all drivers are installed.

I have confirmed that this is the fault of the drive, as several other SSDs that I have work fine in RAID, thus ruling out any board, BIOS, or chipset problem.

Are you suggesting that somehow a secure erase will make the drive work, or are you wondering if I have tried a secure erase to see if it shuts down the drive, as it has with previous models? In case of the latter, I have not attempted a secure erase at all.

I can understand a mistake in development, so therefore I will be contacting Samsung to see if I can get either confirmation that they know about the issue and are working on a fix, a replacement drive of a different model, or my money back. How they answer will determine whether they are up to snuff as a reliable company or not. I will post results back when I get them. Reply
frief - Sunday, December 09, 2012 - link
Hi longtom,

> In case of the latter, I have not attempted a secure erase at all.

Yes, the latter. It's good if these can be kept separate issues. Reply
Kristian Vättö - Sunday, December 09, 2012 - link
Definitely contact Samsung then. Validation is always limited to certain setups, so it's possible that not so common setups face a bug (unfortunately this usually means AMD). Especially RAID is probably not tested on every possible setup that exists given that the regular 840 is mainly meant for mainstream users (who don't even know what RAID is). This happens a lot with laptops because the OEMs often customize BIOS which can cause issues.

If you can't get any proper help through the regular customer service, drop me an email (kristian[AT]anandtech[DOT]com) and I'll forward it to the right people. Reply
Kristian Vättö - Monday, December 10, 2012 - link
longtom,

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