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Discussion Starter #1
Edit by Sean Webster:<br><br>
Thanks to everyone who has posted in this thread and spread the word on the matter, Samsung has taken note of the Samsung Evo Series SSDs degrading performance of older data. A firmware fix for the issue is scheduled to be released October 15th.<br><br>
Furthermore, I would like to personally thank Techie007 and BrainSplatter for their developing of benchmark software to verify this issue.<br><br>
Their latest testing software is located here: <a href="http://www.overclock.net/t/1512915/read-speeds-dropping-dramatically-on-older-files-benchmarks-needed-to-confirm-affected-ssds">http://www.overclock.net/t/1512915/read-speeds-dropping-dramatically-on-older-files-benchmarks-needed-to-confirm-affected-ssds</a><br><hr class="bbcode_rule">
Hi to all!<br>
In my system I have 3 Samsung SSD drives:<br>
1: 256 840 PRO with Windows 7 OS and programs<br>
2: 500GB 840 EVO<br>
3: 1TB 840 EVO<br><br>
Both EVO drives have the same exact problem, read speed on old files drops with time as low as ~60Mb/sec. New written files instead are as fast as advertised read/write speed ~450Mb/sec and so if I start a new benchmark with any benchmarking app.<br>
Please note that the data must be "old" in terms of weeks or months to show the problem. Newly-written data read speed is fast as advertised, this is why benckmarks shows always a fast drive..<br><br>
After a reboot the read speed improves a bit, but not much (as also reported in another thread, don't remember where) and after some "on" time return to the pre-reboot speed.<br><br>
This seems to me a common hardware problem of those cheap SSD...<br>
Anyone with those SSD with old data on it, may do some read speed test?<br><br>
One good test for this is using the good old HDTach v3 program. It will show very well the drop on read speed on disk zones where old data is, using the "long bench" option. It works very well on windows 7 in XP compatibility mode.<br><br>
This seems to me a serious problem on these disks. I have also a 256 840 PRO which does not have the problem (same PC and all SSD connected to INTEL AHCI ports, well configured).<br><br>
To illustrate, here is a HDTach bitmap of my 500 EVO, where the last part is "free" space:<br><a class="H-lightbox-open" href="http://www.overclock.net/content/type/61/id/2136963/"><img alt="" class="lightbox-enabled" data-id="2136963" data-type="61" src="http://www.overclock.net/content/type/61/id/2136963/flags/LL" style="; width: 808px; height: 594px"></a><br><br>
And to compare, here is my 840 PRO, same pc, same AHCI Intel ports:<br><a class="H-lightbox-open" href="http://www.overclock.net/content/type/61/id/2136964/"><img alt="" class="lightbox-enabled" data-id="2136964" data-type="61" src="http://www.overclock.net/content/type/61/id/2136964/flags/LL" style="; width: 808px; height: 594px"></a><br><br>
And as I said, posting a new benchmark is useless as it will be exactly as advertised... The problem is reading old data and it gets worse over time.
 

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Interesting. Can u post your S.M.A.R.T. data? There is a theory that it might be related to a sudden loss of power and the following 'power recovery' procedure:<br><br>
ID # 235 Power Recovery Count:<br><a class="bbcode_url" href="http://www.samsung.com/global/business/semiconductor/minisite/SSD/us/html/about/whitepaper07.html" target="_blank">http://www.samsung.com/global/business/semiconductor/minisite/SSD/us/html/about/whitepaper07.html</a>
 
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subbed , this is an interesting investigation, will have a go at benching if I get time.
 

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I have now seen several reports of this problem on different sites. I own a 1TB EVO since a few days and will try to verify this problem although it supposedly affects 'old' files. But 'old' in all likelihood doesn't mean that you have to leave your SSD lying around for 1 year and then the read data rate even on big 'sequential' files will have dropped significantly. It might rather be related to writing a lot of files or some infrequent event like a sudden system power loss (reset, blue screen, ...).
 

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Very interested to hear what comes of this. I was just debating picking up a 1TB Evo personally.
 

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<div class="quote-container" data-huddler-embed="/t/1507897/samsung-840-evo-read-speed-drops-on-old-written-data-in-the-drive#post_22728663" data-huddler-embed-placeholder="false"><span>Quote:</span>
<div class="quote-block">Originally Posted by <strong>Booty Warrior</strong> <a href="/t/1507897/samsung-840-evo-read-speed-drops-on-old-written-data-in-the-drive#post_22728663"><img alt="View Post" class="inlineimg" src="/img/forum/go_quote.gif"></a><br><br>
Very interested to hear what comes of this. I was just debating picking up a 1TB Evo personally.</div>
</div>
<br>
I think the argument for picking up an Evo is still very valid, the performance gains are insane.<br>
Of course many users still use slow drives for data that's not frequently accessed, which may be something to factor in.
 

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from your print screens i didn't see any old vs new data speed change, so that's probably an illusion of yours.<br><br>
All i could see is that the free space of your ssd has higher read speeds, so check if your trim is enabled.<br><br>
also hd tach is pretty much outdated and created for hdds.<br><br>
use newer benchmark software
 

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<div class="quote-container" data-huddler-embed="/t/1507897/samsung-840-evo-read-speed-drops-on-old-written-data-in-the-drive#post_22728698" data-huddler-embed-placeholder="false"><span>Quote:</span>
<div class="quote-block">Originally Posted by <strong>Eddie Obscurant</strong> <a href="/t/1507897/samsung-840-evo-read-speed-drops-on-old-written-data-in-the-drive#post_22728698"><img alt="View Post" class="inlineimg" src="/img/forum/go_quote.gif"></a><br><br>
also hd tach is pretty much outdated and created for hdds.<br><br>
use newer benchmark software</div>
</div>
<br>
This is true but as I have seen in other similar reports, the problem was usually noticed when people copied big 'old' files and noticed that the performace was much worse than it should be.<br><br>
The easiest test would be to find an old big file (multiple gigabytes if possible) and copy it to another fast SSD. If performance is much lower than 300MB/s then there is something wrong.
 

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Discussion Starter #9
<div class="quote-container" data-huddler-embed="/t/1507897/samsung-840-evo-read-speed-drops-on-old-written-data-in-the-drive#post_22729226" data-huddler-embed-placeholder="false"><span>Quote:</span>
<div class="quote-block">Originally Posted by <strong>BrainSplatter</strong> <a href="/t/1507897/samsung-840-evo-read-speed-drops-on-old-written-data-in-the-drive#post_22729226"><img alt="View Post" class="inlineimg" src="/img/forum/go_quote.gif"></a><br><br>
This is true but as I have seen in other similar reports, the problem was usually noticed when people copied big 'old' files and noticed that the performace was much worse than it should be.<br><br>
The easiest test would be to find an old big file (multiple gigabytes if possible) and copy it to another fast SSD. If performance is much lower than 300MB/s then there is something wrong.</div>
</div>
<br>
This is exactly how I saw the problem the first time. I moved a big file (virtual machine disk file) from the EVO drive to the 840 PRO and the copy speed was less than 100MB/sec. Did the opposite and the speed was ~500MB/sec.<br><br>
After that I did a lot of tests with new and "old-written" files and I'm pretty sure of the problem.<br>
To better explain to you, I'll repeat a test I already did to investigate the problem:<br>
I'll move some big files (two complete VMs) from the EVO to the PRO and back, testing the EVO drive with HDTach before, without the files (after trim) and with the files copied back.<br>
This time the file copy speed ranged from 150MB/sec to 260MB/sec from EVO 500GB to the SSD 840 PRO 256 (~100GB total). Copying the files back to the EVO was very fast as expected: 400-450MB/sec.<br>
Here are HDTach measurements:<br>
Before:<br><img alt="qDwZh7V.png" class="bbcode_img" src="http://i.imgur.com/qDwZh7V.png"><br>
Without files (after some trim time):<br><img alt="ByeGWBy.png" class="bbcode_img" src="http://i.imgur.com/ByeGWBy.png"><br>
Files back to it:<br><img alt="6yT7ZdB.png" class="bbcode_img" src="http://i.imgur.com/6yT7ZdB.png"><br><br>
@Eddie Obscurant: trim affects writing performance (a not-trimmed drive need first to clear memory cells before writing new data) not reading speed. Anyway in my system is working OK, otherwise also the PRO drive will be affected but that's not the case.<br>
To show the problem we need a benchmark program that reads existing data from the drive. Most SSD benchmarks write and than read new files for benchmarking and the speed will be at max!<br>
May you suggest a newer benchmark program that measure read speed of exisiting data? I'll gladly execute that.<br><br>
Finally that's a SMART of the drive:<br><img alt="2r5RBaX.png" class="bbcode_img" src="http://i.imgur.com/2r5RBaX.png">
 

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Discussion Starter #10
<div class="quote-container" data-huddler-embed="/t/1507897/samsung-840-evo-read-speed-drops-on-old-written-data-in-the-drive#post_22728483" data-huddler-embed-placeholder="false"><span>Quote:</span>
<div class="quote-block">Originally Posted by <strong>BrainSplatter</strong> <a href="/t/1507897/samsung-840-evo-read-speed-drops-on-old-written-data-in-the-drive#post_22728483"><img alt="View Post" class="inlineimg" src="/img/forum/go_quote.gif"></a><br><br>
Interesting. Can u post your S.M.A.R.T. data? There is a theory that it might be related to a sudden loss of power and the following 'power recovery' procedure:<br><br>
ID # 235 Power Recovery Count:<br><a class="bbcode_url" href="http://www.samsung.com/global/business/semiconductor/minisite/SSD/us/html/about/whitepaper07.html" target="_blank">http://www.samsung.com/global/business/semiconductor/minisite/SSD/us/html/about/whitepaper07.html</a></div>
</div>
<br>
About that theory... May you point me to these discussions?<br><br>
My system currently in under UPS and it's many months it did not have a power loss or a BSOD. Only normal shutdowns/restarts, but usually it's on 24/7.<br>
BUT after I bought the EVO drive I did some experiments "on the fly" with it by connecting and disconnecting it as external drive and this may have raised that counter. But after these tests, I reformatted it and put it online.<br><br>
Maybe I should check if a normal shutdown on my system will raise that number, though.
 

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Perhaps there's something different (firmware?) with regards to how the drive handles TRIM/GC?<br><br>
The speeds you state sound like what you would see if the data were residing entirely on single NAND chips, just a thought...
 

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<div class="quote-container" data-huddler-embed="/t/1507897/samsung-840-evo-read-speed-drops-on-old-written-data-in-the-drive#post_22729910" data-huddler-embed-placeholder="false"><span>Quote:</span>
<div class="quote-block">Originally Posted by <strong>gino074</strong> <a href="/t/1507897/samsung-840-evo-read-speed-drops-on-old-written-data-in-the-drive#post_22729910"><img alt="View Post" class="inlineimg" src="/img/forum/go_quote.gif"></a><br><br>
About that theory... May you point me to these discussions?</div>
</div>
<br>
Sure, but they are in German:<br><a class="bbcode_url" href="http://www.computerbase.de/forum/showthread.php?t=1381604" target="_blank">http://www.computerbase.de/forum/showthread.php?t=1381604</a><br><br>
Also, the theory is just speculation atm.<br><br>
But something else quite interesting is that a defragmentation helped the guy to get all files back up to speed, lol. I know that defragmentation usually is a bad idea for SSDs since they don't fragment like old HDDs and the defragmentation just adds a lot of write accesses.<br><br>
But IF the SSD 'forgot' the internal optimization for old sequential data then a defrag which touches every file might actually help.<br><br>
What he did is to use <a class="bbcode_url" href="http://www.mydefrag.com/" target="_blank">http://www.mydefrag.com/</a> with the <i>Data Disk Monthly</i> profile. This in effect <span style="text-decoration:underline;">rewrote every file</span>, generating about 1TB of writes (on a 1TB drive with 600GB used).<br><br>
After the 'defragmentation':<br><a class="H-lightbox-open" href="http://www.overclock.net/content/type/61/id/2141609/"><img alt="" class="lightbox-enabled" data-id="2141609" data-type="61" src="http://www.overclock.net/content/type/61/id/2141609/width/200/height/400/flags/LL" style="; width: 200px; height: 162px"></a><br><br><br>
Oh and with this tool <a class="bbcode_url" href="http://thesz.diecru.eu/content/parkdale.php" target="_blank">http://thesz.diecru.eu/content/parkdale.php</a> you can check the read speed for any existing file.
 

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Discussion Starter #13
Hi to all, I have to add a sad follow-up.<br>
Today I asked my colleagues in my office, and found one that "upgraded" his notebook with a samsung 500 EVO. I asked him to do a HDTach scan... Here the result:<br><img alt="COaeueb.png" class="bbcode_img" src="http://i.imgur.com/COaeueb.png"><br>
Of course in normal usage, the laptop is still much much faster than with a mechanical drive, but look at those 40MB/sec drive portions!!!!<br><br>
I'm really thinking these EVO drives are really CRAP! My wild guess is that written TLC memory becomes hard to read as time passes... Or the controller has serious problems!<br><br>
In my opinion we should review again these drives and let people know of these problems, as I'm starting to think that all EVO drives are affected. Maybe also samsung can give us a word...
 

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<div class="quote-container" data-huddler-embed="/t/1507897/samsung-840-evo-read-speed-drops-on-old-written-data-in-the-drive/10#post_22733243" data-huddler-embed-placeholder="false"><span>Quote:</span>
<div class="quote-block">Originally Posted by <strong>gino074</strong> <a href="/t/1507897/samsung-840-evo-read-speed-drops-on-old-written-data-in-the-drive/10#post_22733243"><img alt="View Post" class="inlineimg" src="/img/forum/go_quote.gif"></a><br><br>
Hi to all, I have to add a sad follow-up.<br>
Today I asked my colleagues in my office, and found one that "upgraded" his notebook with a samsung 500 EVO. I asked him to do a HDTach scan... Here the result:<br><img alt="COaeueb.png" class="bbcode_img" src="http://i.imgur.com/COaeueb.png"><br>
Of course in normal usage, the laptop is still much much faster than with a mechanical drive, but look at those 40MB/sec drive portions!!!!<br><br>
I'm really thinking these EVO drives are really CRAP! My wild guess is that written TLC memory becomes hard to read as time passes... Or the controller has serious problems!<br><br>
In my opinion we should review again these drives and let people know of these problems, as I'm starting to think that all EVO drives are affected. Maybe also samsung can give us a word...</div>
</div>
<br>
that's why I sold one of my 3 EVOs, obught an 850 PRO 512GB SSD for super fast and consistent performance and kept the other EVOs for storing my videos/pics/music<br><br>
When I had the EVO and had the OS installed on it, the benchmarks results were so inconsistent sometimes you'd think that's not the EVO you're benchmarking but some other drive.<br><br>
EVOs suck for performance but are great for cheap SSD large storage
 

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Discussion Starter #15
<div class="quote-container" data-huddler-embed="/t/1507897/samsung-840-evo-read-speed-drops-on-old-written-data-in-the-drive/10#post_22734342" data-huddler-embed-placeholder="false"><span>Quote:</span>
<div class="quote-block">Originally Posted by <strong>MaXimus666</strong> <a href="/t/1507897/samsung-840-evo-read-speed-drops-on-old-written-data-in-the-drive/10#post_22734342"><img alt="View Post" class="inlineimg" src="/img/forum/go_quote.gif"></a><br><br>
that's why I sold one of my 3 EVOs, obught an 850 PRO 512GB SSD for super fast and consistent performance and kept the other EVOs for storing my videos/pics/music<br><br>
When I had the EVO and had the OS installed on it, the benchmarks results were so inconsistent sometimes you'd think that's not the EVO you're benchmarking but some other drive.<br><br>
EVOs suck for performance but are great for cheap SSD large storage</div>
</div>
Yes, but what's the point to have an SSD reading as low as 40MB/s? Really at samsung they don't know about this behaviour??<br>
And for large storage I disagree: a mechanical drive is still a better choice and a lot cheaper then the EVOs... Even faster! With the same EVO price you can even set-up a RAID1...<br><br>
Are there other people with an old-enough EVO drive to confirm this behavior?
 

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<div class="quote-container" data-huddler-embed="/t/1507897/samsung-840-evo-read-speed-drops-on-old-written-data-in-the-drive/10#post_22734568" data-huddler-embed-placeholder="false"><span>Quote:</span>
<div class="quote-block">Originally Posted by <strong>gino074</strong> <a href="/t/1507897/samsung-840-evo-read-speed-drops-on-old-written-data-in-the-drive/10#post_22734568"><img alt="View Post" class="inlineimg" src="/img/forum/go_quote.gif"></a><br><br>
Yes, but what's the point to have an SSD reading as low as 40MB/s? Really at samsung they don't know about this behaviour??<br>
And for large storage I disagree: a mechanical drive is still a better choice and a lot cheaper then the EVOs... Even faster! With the same EVO price you can even set-up a RAID1...<br><br>
Are there other people with an old-enough EVO drive to confirm this behavior?</div>
</div>
<br><br><br>
no matter how slow an EVO gets it would smoke the living hell out of a RAID 0 of HDDs PERIOD<br><br>
4K speeds wise an HDD be it single or RAID is gonna crawl like a turtle<br><br>
as to why such inconsistent scores...there's no trick here, TLC, period. It sucks so bad in real world performance and in sustained performance<br><br>
speaking of real world performance,<br><br>
you must see this benchmark:<br><br>
<a href="http://www.anandtech.com/bench/SSD/261" target="_blank">http://www.anandtech.com/bench/SSD/261</a>
 

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Discussion Starter #17
Well that test puts the EVO drives just below the best drives! And that plus the price tag should suggest a best buy...<br><br>
These are exacltly the kind of tests that fooled me on buying the EVOs. And I'm curious now to know if the new samsung MLC V-NAND will exibit a same problem with time. I'll never buy a new samsung drive ever!<br><br>
BTW, how fast are your EVO drives now? May you do a scan of yours and post the results?<br><br>
OT: if you store something like large video files in the drive, a recent 7.2K mechanical drive will read it at 130MB+/sec. When I copied one old file from my EVO it read it at ~60MB/sec... Of course for everything else like parallel access or many smaller files you are obviously right!
 

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Discussion Starter #18
<div class="quote-container" data-huddler-embed="/t/1507897/samsung-840-evo-read-speed-drops-on-old-written-data-in-the-drive/10#post_22733030" data-huddler-embed-placeholder="false"><span>Quote:</span>
<div class="quote-block">Originally Posted by <strong>BrainSplatter</strong> <a href="/t/1507897/samsung-840-evo-read-speed-drops-on-old-written-data-in-the-drive/10#post_22733030"><img alt="View Post" class="inlineimg" src="/img/forum/go_quote.gif"></a><br><br>
Sure, but they are in German:<br><a class="bbcode_url" href="http://www.computerbase.de/forum/showthread.php?t=1381604" target="_blank">http://www.computerbase.de/forum/showthread.php?t=1381604</a><br>
Also, the theory is just speculation atm.<br>
But something else quite interesting is that a defragmentation helped the guy to get all files back up to speed, lol. I know that defragmentation usually is a bad idea for SSDs since they don't fragment like old HDDs and the defragmentation just adds a lot of write accesses.</div>
</div>
<br>
Well defragmenting the whole drive rewrites all the data blocks... Now even without going too far with speculations, it is a fact that with these EVO drives newly written data are "normally" fast, as also proven by my previous test. So rewriting all blocks or copying back file by file is the same result (but defrag writes much more = really bad idea).<br><div class="quote-container" data-huddler-embed="/t/1507897/samsung-840-evo-read-speed-drops-on-old-written-data-in-the-drive/10#post_22733030" data-huddler-embed-placeholder="false"><span>Quote:</span>
<div class="quote-block">Originally Posted by <strong>BrainSplatter</strong> <a href="/t/1507897/samsung-840-evo-read-speed-drops-on-old-written-data-in-the-drive/10#post_22733030"><img alt="View Post" class="inlineimg" src="/img/forum/go_quote.gif"></a><br><br>
Oh and with this tool <a class="bbcode_url" href="http://thesz.diecru.eu/content/parkdale.php" target="_blank">http://thesz.diecru.eu/content/parkdale.php</a> you can check the read speed for any existing file.</div>
</div>
<br>
Thanks a lot, in that tool there is also a "block access" tool that can do a linear scan of the disk, also more accurate than HDTach. But taken apart some numeric differences due to the configuration of reading block size, etc, both speed graphs are basically the same.<br><br>
Only Samsung knows if this is something that can be impreved in the firmware, but I don't have much hope on that if it is a physical limitation of TLC memory!
 

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<div class="quote-container" data-huddler-embed="/t/1507897/samsung-840-evo-read-speed-drops-on-old-written-data-in-the-drive/10#post_22734963" data-huddler-embed-placeholder="false"><span>Quote:</span>
<div class="quote-block">Originally Posted by <strong>gino074</strong> <a href="/t/1507897/samsung-840-evo-read-speed-drops-on-old-written-data-in-the-drive/10#post_22734963"><img alt="View Post" class="inlineimg" src="/img/forum/go_quote.gif"></a><br><br>
Well that test puts the EVO drives just below the best drives! And that plus the price tag should suggest a best buy...<br><br>
These are exacltly the kind of tests that fooled me on buying the EVOs. And I'm curious now to know if the new samsung MLC V-NAND will exibit a same problem with time. I'll never buy a new samsung drive ever!<br><br>
BTW, how fast are your EVO drives now? May you do a scan of yours and post the results?<br><br>
OT: if you store something like large video files in the drive, a recent 7.2K mechanical drive will read it at 130MB+/sec. When I copied one old file from my EVO it read it at ~60MB/sec... Of course for everything else like parallel access or many smaller files you are obviously right!</div>
</div>
<br>
do a scan of my drives and post the results? what scan?
 

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subbed to this, as i've just ordered an EVO 256GB. Since it'll be a clean drive, is there any tests I can do?
 
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