Samsung 840 and 840 EVO Performance Degradation

[Mystik]

Do you own a Samsung 840 or 840 EVO SSD? If not, this topic doesn't concern you. If yes, read on!

Problem

The problem is that after some time, their performance will decrease drastically.

Technical details

The issue has to do with older blocks of data: reading old files is consistently slower than normal – as slow as ~30MB/s – whereas newly written files, like the ones used in benchmarks, perform as fast as new – around 500MB/s for the well regarded SSD 840 EVO. The reason no one had noticed (we reviewed the drive back in September 2013) is that data has to be several weeks old to show the problem.

http://www.techspot.com/article/997-sams...gradation/
http://www.pcper.com/reviews/Editorial/S...-over-time
http://www.pcper.com/reviews/Storage/Sam...back-speed
http://www.pcper.com/reviews/Storage/Sam...ally-Fixed

There has been a lot of talk about this in various forums and websites, but i prefer to share my own experiences instead. These screenshots are from a test that reads all data on the SSD, and shows the speeds as the data is read. This first screenshot is after i had used my 840 EVO 250GB for a few months:



The SSD is supposed to be able to read the data at around 520 mb/s stable but obviously it's not doing so, as read speed drops all the way down to 52.1 mb/s can be seen. Now let's keep this image in mind and continue.

Samsung has acknowledged the problem and they have been working on a fix for quite some time now, and they have released multiple firmware updates and tools to help fix the problem. They even released a program to restore the 840 EVO performance. But these were not complete fixes, as the problem will continue after some time, just like it started.
But now Samsung has finally released a firmware / software combination that should fix the problem, or so they claim.


Solution

Like mentioned in the articles, the problem is that when data has been on the memory cells for a long time, it becomes slower to read. This would be solved by rewriting all data on SSD, but that is just a temporary solution, and this is where the new firmware comes into play. The new firmware will enable the memory cells to rewrite data so it stays "fresh" and up to speed. This will obviously reduce the lifetime of the cells a tiny bit, but shouldn't be noticeable. However doing the full rewrite of data would be, so that's why the firmware is a better alternative, as you just have to rewrite everything once, and then the firmware will do the rest in the future.
DISCLAIMER: I'm not responsible for anything, including but not limited to: data loss, broken drives, global warming, UFO kidnappings or the inevitable doom of the world.
LETS FIX THIS!

1) Get the Samsung Magician 4.6 software here.
NOTE: At this point i recommend doing a full drive backup / image just in case. I didn't loose any data, but better to be safe than sorry.

2) Go to the Update firmware section from the left sidebar, and follow the instructions to update the latest firmware. (Will ask to reboot etc accordingly)


And now, we will already begin to see some improvements. Let's take the read speed test again:

As you can see, a bit better already! Now, let's get to real business!

3) Now that your firmware is updated go to the Performance optimization section and the Advanced tab.
(Also check that the firmware tab is saying that you have the latest firmware EXT0DB6Q)


NOTE: Like the warning says, this will take a long time (An hour or so if i recall right) and i wouldn't recommend doing a lot of data read / writes to that drive in the meanwhile.

4) Press start and wait for it to complete

And now we are all done! So was this worth it? Behold, the final read test:



Future

So now what? Everything is fine in Happy Town? Problem is fixed for good now! Not so fast... This isn't a fix in my opinion, it's more like applying a band aid to a wound: It helps, but doesn't cure the wound. Sure, this will fix the performance degradation, but at the cost of flash cell lifetime, and how is this a problem in the first place? Makes me question my future purchases: Can i trust that the cheaper Samsung models will deliver a good enough performance too? Well luckily it has been documented that the 850 EVO's 3D NAND are much more durable, and a thing like the 840 fiasco shouldn't happen again with the 850 EVOs, but i guess only time will tell...

[Andre]

Thank you so much for this thread. mine ssd ( same as yours) started to get slower read again even after the samsung first try of fixing it with the firmware of october ( or around there) months by months ( instead of 500 stable, it was running at like 300 or less). for some reason i missed the update both of magician and firmware.
after having updated both of them now the ssd runs back to 500 stable. awesome!

can't thanks you enough

about the 850, it should have not anymore that problem since it has V nand. but i can't be 100% sure.

keep these threads ups, good work!