Samsung 840 evo

[Joe-912]

Just wanted to share with other samsung ssd evo owners, last year I had a problem with read performance with my 250GB evo samsung ssd, I did a secure errase which fixed my problem, but it returned a few months later.
Last month I found out it was due to a error in the software algorithm, the 840 EVO performed read-retry processes aggressively, resulting in a drop in overall read performance."
"A drop in performance occurs on data stored for a long period of time and [that] has been written only once. SSDs usually calibrate changes in the statuses of cells over time via the flash management software algorithm.

AnandTech | Samsung Releases Firmware Update to Fix the SSD 840 EVO Read Performance Bug

I downloaded new firmware and attached is a tool that fixes the data stored on ssd, this was released last October but I only found out about Jan this year, it worked my os was working after fine, make sure you got a backup image before running the fix..
Hopeit helps any samsung evo ssd owners
Joe

[Britgeezer]

Re: Samsung 840 evo

Hmmm,

Thanks for the info, reading the article even though I have the latest firmware I should run this SW. Just concerned to be fixing something, I don't see as broken.

Update: I just completed the restoration. Random write unchanged. Sequential index improved from 302/392 to 394/ 392. I guess there was a need.

[Joe-912]

Re: Samsung 840 evo

It took about half hour to complete when I run the tool, I used to get problem with backups they would take about 4 time longer, but alls well so far..

[parsec]

Re: Samsung 840 evo

The apparent issue with the Samsung 840 EVO SSD is more complex than just applying the fix provided by Samsung.

The genesis of this issue can be found in at least one thread in the OCN SSD forum:

Samsung 840 EVO read speed drops on old-written data in the drive

[PETITION] Samsung 840 SSD Series Read Degradation issue - Petition for Replacement

If you read through a few pages (out of 192) at the end of the first thread posted above, some 840 EVO owners claim that the fix is only temporary. Other claims found in that thread seem to say that only some 840 EVOs are affected by this problem.

At this time, few (if any) PC enthusiast web sites are saying that the 840 EVO has a definite issue. Reporting that Samsung has released a program that fixes the apparent problem by some PC enthusiast web sites is not equivalent to an editorial stating that a problem exists with the 840 EVO. Unfortunately, some people believe that it does.

IMO the apparent reluctance of the PC enthusiast media to jump on this situation is justified. There is more to it than comparing benchmark results with a few programs. I cannot say that this issue does or does not exist, but I do know that SSD performance is not static. It will change when comparing a new, unused SSD's benchmark results with those of a SSD half filled with data, and/or used as an OS drive.

While the tests used to "demonstrate" the issue look bad, I don't feel qualified enough to pass judgement on something as highly technical and complex as the internal operation of any SSD.

Yes it appears SSDs that do not use TLC NAND do not show the same poor results when tested in the same way. The fix provided by Samsung does change the test results. I just know that many apparent issues with PC hardware have turned out to be something else, so I cannot pass any judgement about this situation.

[Joe-912]

[parsec]

Re: Samsung 840 evo

I have nothing against the 840 EVO, I have one. Its QD 1 4K random read speed is unsurpassed, not the 840 Pro or 850 Pro beat it, or the SanDisk Extreme Pro or Extreme II. The Samsung XP941 PCIe SSD also is not faster or even equal to a Samsung EVO (250GB or greater) in 4K random read speed.

The difference may not seem like much, ~2 - 5MB/s for the SSDs I mentioned, but at the 4K random read speed of SSDs, that is a 5 - 10% difference. HDDs have 4K random read speeds of less than 1MB/s.

That small file random read speed makes it great as an OS drive, particularly for booting an OS.

The issue with the 840 EVO is that large files of multi-megabyte size that are "old", meaning not accessed frequently like a data backup, when eventually read are retrieved at very low speeds, under 100MB/s, rather than the usual ~500MB/s specified read speed.

We have at least two specific conditions that must be true about the data being read, before any performance problem is apparent. Which means all the other aspects of the EVO's performance are not affected. Plus there is a fix created by Samsung to address the apparent problem with data in the conditions I described.

So there is no reason to apologize for purchasing an 840 EVO. Six months ago it was probably the most popular SSD model in the world. I would not be concerned about replacing it. The main thing to ask yourself is, do you think your 840 EVO is performing worse in any way now compared to when you began using it. If it is, then run the special fix program, which performs a firmware update and rewrites all the data on the SSD.

[Joe-912]

Re: Samsung 840 evo

Well a few months if you remember I was having a bit of trouble with my Backup Images taking aprox 4 times as long as they used to, so the read performance went bad after about 3-4 months first time I did secure errase and it was back to normal, this is before I knew about the Firmware fix, but as I mentioned in my post earlier I have already applied the fix in January and alls well, As for happy with the evo yes as long as I don't have to keep messing around appling fixes, as for upgrading I would go for a 512GB next time anyway, the 850 Pros are nice but the price is way too much IMO,
Thanks
joe