Samsung 840 Evo SSD Performance Degradation

[eJoculate]

There have been several reports going around lately about Samsung 840 Evo SSDs experiencing read speed drops with older files.
The main catalyst being the Overclock forum in this here thread.

Several users have independently tested their read speeds and the consensus can be summed up by this reddit post:

 

I just tested this myself on my 250GB 840 Evo:

I read a 6 month(power on hours) old file that is 8.5GB and it took 274 seconds with an average transfer rate of 31.8 MB/s

I read a new 3.7GB file ( ~ 48 power on hours) in 8 seconds with an average transfer rate of 473.6 MB/s

I cleared my disk cache before each test.

EDIT: More testing

I've clear my cache and read the file 4 more times

• Read #2: 46.4 MB/s
• Read #3: 49.5 MB/s
• Read #4: 51.2 MB/s
• Read #5: 52.1 MB/s

 

 

 

For the more visually inclined amongst us:

 

Exhibit A: Samsung 840 EVO - 500GB

 

Exhibit B: Samsung 840 EVO - 1TB

 

 

Analysis:

• Drastic degradation can begin as early as 3+ month aged files
• Currently appears to only affect the 840 EVO line

Speculations:

• Garbage Collection / Wear Levelling issue
• TLC NAND issue

Current Solutions:

While awaiting an official response/update from Samsung, a possible solution to regain SSD level read speeds would be to defragment ^{(yes, you read that right)} the SSD. This is due to the current degradation of read speed being caused by files aging (from time last written); thus a process to relocate those files creates fresh write cycles and restores the read speed levels. Several users in the linked threads have attested to this method being effective, albeit at a cost to SSD longevity.

 

 

 

(longtime lurker, first time poster here; read the rules for posting in this section and searched ahead of time for coverage on this issue to ensure it wasn't already discussed. Apologies if I have failed miserably in my quest to create a rule abiding post.)

Edited September 13, 2014 by eJoculate

[Sexy Vanilla Freshness]

 Please tell me more about how TLC NAND is a wise choice.

 

At this price point we now have the Crucial MX100 with a solid controller and MLC flash, yet still people flock to 840 EVO in droves, why?

[Sidiox]

Very interesting. And the EVO line was doing so well...

This could really kill the drive as a boot drive as usually you keep those files on it for very long without changing them

I really hope they can find a solution to this and not by defragmenting.....

 

Edit:

@eJoculate good post btw

[GM_Peka]

Wow, good job on the first post, you did good son.

 

Makes me question thing. I wonder If the 850 Evo will have any issues, maybe Samsung already know about this, who knows.

 

Maybe I'll try stick to the m550 instead :3.

[qwertywarrior]

 since its just happening on the EVO drives then TLC might not be the culprut since the pro and the standard model is also TLC.

The only new thing with the EVO ssds is that its 19nm TLC or what samsung likes to call it 1x nm class , sata 3.1, a speed bump for the controller from 300mhz  to 400mhz  and queued TRIM commands 

 

could be a firmware issue with how it handles the new queued TRIM commands

[Ren]

Please tell me more about how TLC NAND is a wise choice.

 

At this price point we now have the Crucial MX100 with a solid controller and MLC flash, yet still people flock to 840 EVO in droves, why?

In North America (and likely most of Europe as well), the MX100 is actually much cheaper .

Why? I think it has to do with a built up reputation and people being clueless. Lots of people don't really pay attention to all of the important stuff and hear about it from this guy and this guy and that guy*, so it must be good. I can admit that I wouldn't know everything about SSDs (basically too little research outside of the controller and even then,...). This definitely surprised me but I don't care. The last time I recommended an EVO drive was back in October of last year, before/during the massive sales going on and before the rise in mining popularity. Since then, it's been the MX100, M500/550 and the PNY drives because of how much cheaper they are regularly and on sale.

Still think Samsung PROs are good if you have money but maybe Sandisk will take that spot soon. Especially after news like this (although, 850..). In any case, competition is getting stiffer. I'm glad people might pay attention to other brands now.

*Blame people on /r/buildapc for recommending nothing but Samsung EVOs for 8 months straight, basically.

Edit: Nice first post, keep 'em coming.

[GoncaloMoreno]

I had this problem with my 840 evo (120gb). I used a program written by brainsplatter (File Bench) and the windows folder, which i had since the beggining ( 5 months) and another old folder, had a average read speed of 30 mb/s but new / downloaded folders had a average of 400 mb/s. The booting time was definitly slower (5-8 seconds less) then when i got the drive.  Then i downloaded my defrag program and defraged the ssd ( I know that you shouldnt defrag ssds but this is a special case). After defraggin the ssd the speeds were back to normal and the windows folder was having a average speed of 450+ mb/s. Seems like the evo doesnt like old files but new one it does and deffraging seems like it rewrites all the files. When i was deffraging i was monitor with samsung magician program the toltal bytes written and it jumped from 2.28 TB to 2.36 TB (80gb) which probably wont affect much of the drive lifetime considering that you only need to this every 3+ months.

[Humbug]

Sounds like something Samsung will have to fix via a firmware update.

Until then evo users should not be afraid to defrag. Don't believe all the bs that it will kill your SSD.

[Humbug]

also has anybody tested whether the same problem can be recreated on the 850 pro?

[PopReference]

I've noticed similar issues with my Kingston, not sure, but if anyone on the forum wants to try repeatedly benchmarking their drives to produce similar results?

[Humbug]

I've noticed similar issues with my Kingston, not sure

can You run a test before and after defrag?

[PopReference]

can You run a test before and after defrag?

I'm not unwilling to do this(YOLO SSD) but it will take time and I would have to stop everything to do this, so maybe later.

[brownninja97]

can You run a test before and after defrag?

you cant defrag an ssd, you would kill it

[Me1z]

It might just be that a few people got duds. As far as I can tell, my 500gb 840 Evo is still running as fast as it did the day I installed it. Anyone have a recommended program to use to test it for myself?

[Faceman]

Great first post, excellent formatting, gold star!

[Humbug]

you cant defrag an ssd, you would kill it

Interestingly this is actually a lie which people keep blindly repeating.

You normally don't need to defrag an SSD. It's considered pointless which is why we turn if off.

But doing so does not kill it or harm it.

 

People get paranoid because of the fact that SSDs have finite write cycles in their lifetime. What they do not realize is that defragging does not consume a significant portion of that.

They do not realize that the actual durability and lifespans are way more than what we consumers need or end up using.

 

A lot of the paranoia started because years ago first generation consumer SSDs had some problems (new tech). Tech sites all over capitalized and wrote all kinds of optimization guides to generate hits. Now even though those problems don't exist you will still find otherwise tech savvy people who think that they have to be careful with their modern SSDs, and who think it's dangerous to use them to their max. There are even people on this forum who move page files off SSDs sacrificing performance because they think that the writes are harming their SSDs.

[brownninja97]

Interestingly this is actually a lie which people keep blindly repeating.

You normally don't need to defrag an SSD. It's considered pointless which is why we turn if off.

But doing so does not kill it or harm it.

 

People get paranoid because of the fact that SSDs have finite write cycles in their lifetime. What they do not realize is that defragging does not consume a significant portion of that.

They do not realize that the actual durability and lifespans are way more than what we consumers need or end up using.

 

A lot of the paranoia started because years ago first generation consumer SSDs had some problems (new tech). Tech sites all over capitalized and wrote all kinds of optimization guides to generate hits. Now even though those problems don't exist you will still find otherwise tech savvy people who think that they have to be careful with their modern SSDs, and who think it's dangerous to use them to their max. There are even people on this forum who move page files off SSDs sacrificing performance because they think that the writes are harming their SSDs.

I defragged a samsung 830 and it died so thats what i believed, i guess times have changed, honestly i dont defrag anything anymore, i find that the performance improvement isnt noticeable but thats just me.

[Humbug]

I defragged a samsung 830 and it died so thats what i believed, i guess times have changed, honestly i dont defrag anything anymore, i find that the performance improvement isnt noticeable but thats just me.

Interesting, I would guess it was coincidence, a bad drive that was dying anyway.

Anyway I don't defrag my SSD either. I did once though a year ago just for kicks (Corsair Performance Pro).

[Trik'Stari]

I wonder if the 840 pro will experience this sort of thing.............

[Guest Generallee]

And i'm just sitting here with my perfectly working 830

[WarlockTheWise]

Guess that explains this then:

 

[Rohit Jackdaw]

Very interesting. And the EVO line was doing so well...

This could really kill the drive as a boot drive as usually you keep those files on it for very long without changing them

I really hope they can find a solution to this and not by defragmenting.....

 

Edit:

@eJoculate good post btw

No. In that case boot files are accessed daily. From the example speed starts to increase with each run. But for old files it will cause trouble.

[Bloodyvalley]

Because SSD Magician. (and the SSD itself just looks beyond awesome)

Stupidest comment of the day goes to you, sir.

[snes]

You guys wipe your Windows partitions less than twice a year?

[razor767]

Makes me nervous about buying a 840 EVO now.