Samsung 840 EVO drive very slow read speeds on old files

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ricky1980

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the original thread started at overclock.net but the link below has a pretty comprehensive video explaining what has happened.

in short, the TLC flash memory samsung uses seem to have a problem at holding data longer than 4 weeks before the drive starts to exhibit significant read speed drops. This is speculated that there is some kind of loss of voltage within the flash memory causing a lot of error correction algorithms to be applied thus the speed reduction. the older the files the slower the read speed...some reported to be as slow as 50mb/s which is terrible.

I was tempted to buy one of these for storage luckily came across some posts regarding this upon some research. Samsung is looking at a fix, but I can't help thinking this may not be possible if there is a fundamental design flaw in the logic gates.

so be very careful when you choose your SSDs. this only applies to the 840 EVO and 840 drives as they use the TLC not the MLC flash memories

http://www.pcper.com/reviews/Editor...ptible-flash-read-speed-degradation-over-time
 
thanks for the heads up. I too was being tempted by these beauties although I'm not sure if I'm ever of the PC long enough for this to happen
 
neil_g said:
Interesting. They've been popular drives for some time now and I don't recall reading of these issues anywhere
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the initial issue was raised on 16th September on overclock.net and now it is covered on every single computer forums and tech websites. anandtech also reports this.

http://www.anandtech.com/show/8550/...40-evo-read-performance-bug-fix-is-on-the-way

its quite a real problem, people may not have realised this but as soon as they test it on their old files they report the same issue. some people saying they have noticed a significant windows and game load time decrease when they "defragged" their SSD. yes defrag ssd isnt good as it reduces the write cycle of the flash but that way it forces the drive to write fresh copies of the file and thus making them read fast again...

also that drive was the top seller for the last year, god knows how many of those they shifted...a real problem has massive impact
 
im not doubting you, im just saying its odd that its only been picked up recently.

fwiw im grateful I have the 830, before they handicapt the 840 to get several different grades out of it ;)
 
i am not implying anything neil, i was about to press the button on one of these, until i came across a thread in UK Hot Deals. a singular post by someone. I then did a bit of search on google, it was about 3/4 days ago. funnily the search was extremely hard as it is quite a new issue couldn't find anything on the net. then someone in the same UK hot deal linked in the overclock.net thread then yesterday google search yielded a whole load more results across the IT communities.

I think samsung used the TLC flashes solely on the cheaper 840 variant. thus the 840 non pro and evo is affected and no other samsung drives have been affected. But i am not sure the newer 850 ones will have the same issue as they also use the TLC flashes. the non pro one at least
 
I have the 840 pro :) <phew>
 
neil_g said:
im not saying youre implying anything?

im saying with the amount of users owning this drive that it was not raised with Samsung earlier.
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Benchmarks will show full speed... only old data is affected... that's why it took so long. Who tests how long it takes to read specific files that have been on their drives for a month or longer?

Firmware fix October 15th apparently. Samsung SSD Magician software will patch it for you when it's available.
 
Pookeyhead said:
Benchmarks will show full speed... only old data is affected... that's why it took so long. Who tests how long it takes to read specific files that have been on their drives for a month or longer?

Firmware fix October 15th apparently. Samsung SSD Magician software will patch it for you when it's available.
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indeed indeed. i think when i was looking for SSD last earlier last year read heavily into these flash memories used for the SSD there were a couple of articles regarding the stability of the samsung's cheap TLC gates. so what they did was a torture test, ie wiping and rewrtiting the SSD over and over to see how the performance is affected and the benchmarks found very little signs of performance degradation thus everyone thought these TLC gate are as stable as the proven MLC gates...but no one thought they would leak voltage over time. I don't dare to think samsung engineers knew this would happen.
 
Pookeyhead said:
Benchmarks will show full speed... only old data is affected... that's why it took so long. Who tests how long it takes to read specific files that have been on their drives for a month or longer?

Firmware fix October 15th apparently. Samsung SSD Magician software will patch it for you when it's available.
Click to expand...
Although I'm reading a lot on ocuk that the slowdowns are only apparent on benching and not in real world usage.

At least samsung are releasing a fix shortly :)
 
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