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Message
Anyone running a Samsung 840 EVO SSD should read this (new firmware released)
Posted on 9/19/14 at 2:20 pm
Posted on 9/19/14 at 2:20 pm
I just stumbled across a discussion that's pretty important, affecting Samsung 840 EVO SSDs.
Apparently, the longer a file remains on the SSD, the slower it is to be read. And by slower, I mean MUCH slower. Discussion on Overclock.net:
LINK
The OCN thread is long, but a particular post in it seems to be probably the most valid theory/summary of the problem:
I tested this myself a few minutes ago.
I tested a 2GB sound file in my Watch Dogs game installation folder using Parkdale. I bought my 500GB Evo on August 10, and the file I tested was added to the drive on August 12, so just over 5 weeks ago.
Read: 60MB/s -
I then made a copy of it within the same folder and tested again:
This makes me sad. And Samsung is going to have some furious 840 EVO owners. These have been top performers in basically every test, but unfortunately, reviews are done under file scenarios and not over time.
However, after running MyDefrag v4.3.1 "Flash Memory Disks" option, the original file began to read normally. Defrag processes do a good bit of rewriting to move files around, which would explain the improvement. I'm going to monitor the performance degradation of various static files over the next few weeks, so I have a rough idea of how often I should run this defrag. Since program files and Windows/boot files are seldom/never changed or rewritten, so this can and will affect boot-up/load performance over time unless you use a program to rewrite the files.
The defrag, especially if only done once every few weeks or so, should not significantly reduce the life of your SSD to any span that a normal human tends to keep drives. However, it is quite irritating that this has to be done at all. If it really is just a wear-leveling bug in the controller, Samsung needs to release a firmware update ASAP or they've lost my fanboyism permanently. This does not affect the 840 Pro, however. It's possibly not an issue on any MLC NAND drive.
Until then, ignore any previous instance in any thread where I may have recommended a Samsung 840 EVO.
Apparently, the longer a file remains on the SSD, the slower it is to be read. And by slower, I mean MUCH slower. Discussion on Overclock.net:
LINK
The OCN thread is long, but a particular post in it seems to be probably the most valid theory/summary of the problem:
quote:
@fragamennon
Thanks for the infos! It looks more and more that the EVO has a bug.
In the thread with the same topic on a German website the most likely cause of this issue discussed, is a bug in the 'wear leveling / garbage collection' mechanism of the EVO.
https://www.computerbase.de/forum/showthread.php?t=1381604&page=5
EVO bug theory in short:
- Flash cells can only sustain a limited number of write cycles (writing requires erasing the flash cell)
- If all static data/files would stay in the flash cells to which they have been written to originally, the remaining flash cells would have to endure all the write cycles for changing data and would quickly wear out
- That's why all SSD reorganize old data and writes them into different flash cells, in order to spread the necessary erase cycles as evenly as possible over all flash cells. This is called wear leveling
And if the EVO has a bug in the wear leveling which causes the old data to be rearranged in a disadvantageous configuration for reading (e.g. they are all put into the same flash block so that there is no parallel block reading possible), that would explain the results we see here.
Here is an article which explains the GC/wear leveling:
https://www.thessdreview.com/daily-news/latest-buzz/garbage-collection-and-trim-in-ssds-explained-an-ssd-primer/
I tested this myself a few minutes ago.
I tested a 2GB sound file in my Watch Dogs game installation folder using Parkdale. I bought my 500GB Evo on August 10, and the file I tested was added to the drive on August 12, so just over 5 weeks ago.
Read: 60MB/s -
I then made a copy of it within the same folder and tested again:
This makes me sad. And Samsung is going to have some furious 840 EVO owners. These have been top performers in basically every test, but unfortunately, reviews are done under file scenarios and not over time.
However, after running MyDefrag v4.3.1 "Flash Memory Disks" option, the original file began to read normally. Defrag processes do a good bit of rewriting to move files around, which would explain the improvement. I'm going to monitor the performance degradation of various static files over the next few weeks, so I have a rough idea of how often I should run this defrag. Since program files and Windows/boot files are seldom/never changed or rewritten, so this can and will affect boot-up/load performance over time unless you use a program to rewrite the files.
The defrag, especially if only done once every few weeks or so, should not significantly reduce the life of your SSD to any span that a normal human tends to keep drives. However, it is quite irritating that this has to be done at all. If it really is just a wear-leveling bug in the controller, Samsung needs to release a firmware update ASAP or they've lost my fanboyism permanently. This does not affect the 840 Pro, however. It's possibly not an issue on any MLC NAND drive.
Until then, ignore any previous instance in any thread where I may have recommended a Samsung 840 EVO.
This post was edited on 10/15/14 at 10:31 am
6
Posted on 9/19/14 at 2:25 pm to ILikeLSUToo
But that MByte tho
Yeah I have one,
, hopefully a firmware update is coming
Yeah I have one,
, hopefully a firmware update is coming
Posted on 9/19/14 at 2:29 pm to ILikeLSUToo
Well frick. 
Posted on 9/19/14 at 2:32 pm to ILikeLSUToo
quote:
Until then, ignore any previous instance in any thread where I may have recommended a Samsung 840 EVO.
I actually just bought/transferred my mother's OS to an 840 Evo. Now I just need to figure out how to unintrusively run the defrag at a time she won't be on the computer.
Posted on 9/19/14 at 2:34 pm to ILikeLSUToo
Am I correct in assuming it's the same thing with programs since they don't move?
Also, any ideas on what happens if the files are modified relatively often?
Also, any ideas on what happens if the files are modified relatively often?
Posted on 9/19/14 at 2:37 pm to Hopeful Doc
There may be a better program out there that could run in the background and defrag on a schedule. But the problem with that is making sure your mother isn't the type who turns the computer off any second of the day she's not using it. Since I leave mine active 24/7, I tend to have tasks like backups and defrags run in the middle of the night.
Posted on 9/19/14 at 2:42 pm to junkfunky
quote:
Am I correct in assuming it's the same thing with programs since they don't move?
Yes. The file I tested was a program file tied to the PC game Watch Dogs. It's just a pack of various in-game sounds that is never modified, only read.
quote:
Also, any ideas on what happens if the files are modified relatively often?
Not totally sure. Other than some documents that are too small for a valid test, nothing that I frequently modify is kept on the SSD. A good test for this would be some large project file for AutoCAD or equivalent that was created a while back but edited. I would guess that the read performance on such a thing would be fine, but I just don't have anything valid to test since the test requires time to elapse.
Posted on 9/19/14 at 3:21 pm to ILikeLSUToo
quote:
But the problem with that is making sure your mother isn't the type who turns the computer off any second of the day she's not using it.
Nah, I've got her trained. The SSD images itself to a 3.5" 3tb internal drive. All her media, by default, goes directly to directories on the HDD. I did clone it originally because I didn't want to go through and sort out what the 100GB or so of date she had already, but she'll also essentially never run it above 120GB (hers is a 240GB drive if I didn't say that earlier). She doesn't download anything. The children who are still around the house have barely more than guest privileges to the computer.
So there's little chance she runs the drive near capacity (as I understand it, a crippling state for an ssd), and she wouldn't notice if I had a little scripted program or one that allows itself to be scheduled running in the background.
Posted on 9/19/14 at 3:36 pm to Hopeful Doc
This is timely, posted this afternoon:
Samsung Acknowledges the SSD 840 EVO Read Performance Bug - Fix Is on the Way
If they can get the firmware out within a couple of weeks, you may not have to worry about scheduling defrags for her, just update the firmware and hopefully that'll be the end of it.
Samsung Acknowledges the SSD 840 EVO Read Performance Bug - Fix Is on the Way
If they can get the firmware out within a couple of weeks, you may not have to worry about scheduling defrags for her, just update the firmware and hopefully that'll be the end of it.
This post was edited on 9/19/14 at 3:37 pm
Posted on 9/19/14 at 3:37 pm to ILikeLSUToo
I assume I'm fine with the 840 pros?
Posted on 9/29/14 at 7:35 pm to ILikeLSUToo
FYI, look for a firmware update on October 15
LINK
LINK
Posted on 9/29/14 at 9:14 pm to ILikeLSUToo
Does Samsung 830 look unaffected? Running that on my laptop.
Posted on 9/29/14 at 9:42 pm to ILikeLSUToo
quote:
ILikeLSUToo
Many upvotes for your attention to this.
Posted on 9/29/14 at 11:04 pm to busbeepbeep
quote:
Does Samsung 830 look unaffected? Running that on my laptop.
No affect on the 830. I have one of those as well.
Posted on 9/29/14 at 11:55 pm to ILikeLSUToo
When the firmware update comes I will obviously download it, but will I need to do anything before then since you're talking about doing defrag now? Or will this fix everything you think?
Posted on 9/30/14 at 12:14 am to Sho Nuff
Not sure. It's probably a good idea to do a defrag after installing the new firmware. It's supposedly an update to the controller, and it may only change the way the controller handles data this point forward. Samsung might have some release notes to clear that up.
I downloaded DiskFresh. Seems to do a better job than the other defrag program I used. LINK
I downloaded DiskFresh. Seems to do a better job than the other defrag program I used. LINK
Posted on 9/30/14 at 10:20 pm to ILikeLSUToo
Thanks for the response, I'll wait to see what the release notes say 
Posted on 10/15/14 at 10:29 am to Sho Nuff
Here's a direct link to download the fix:
LINK
Extract and run the program. It's a "Performance Restoration" program that first installs the new firmware, reboots your PC (or in my case turned it off and I had to turn it back on myself), then rewrites every block to refresh the drive. Takes a little while to do that part if you have a lot of data.
If there's something on the drive you don't want to lose, I'd recommend doing a backup beforehand, because shite can happen. (Full disclosure: I installed the firmware and did the refresh without backing anything up, and there were no issues, but I don't always practice what I preach and nothing on my SSD is irreplaceable).
Here's Samsung's official statement on the bug:
To summarize an article on PC Perspective, cell voltages in flash memory shift over time, and controllers are designed to correct and adjust voltage thresholds as it sees errors. The EVO wasn't doing that but instead trying to perform error correction on all data when its cells drifted far enough to the default voltage threshold.
LINK
Extract and run the program. It's a "Performance Restoration" program that first installs the new firmware, reboots your PC (or in my case turned it off and I had to turn it back on myself), then rewrites every block to refresh the drive. Takes a little while to do that part if you have a lot of data.
If there's something on the drive you don't want to lose, I'd recommend doing a backup beforehand, because shite can happen. (Full disclosure: I installed the firmware and did the refresh without backing anything up, and there were no issues, but I don't always practice what I preach and nothing on my SSD is irreplaceable).
Here's Samsung's official statement on the bug:
quote:
ecause of an error in the flash management software algorithm in the 840 EVO, a drop in performance occurs on data stored for a long period of time AND has been written only once. SSDs usually calibrate changes in the statuses of cells over time via the flash management software algorithm. Due to the error in the software algorithm, the 840 EVO performed read-retry processes aggressively, resulting in a drop in overall read performance.
This only occurs if the data was kept in its initial cell without changing, and there are no symptoms of reduced read performance if the data was subsequently migrated from those cells or overwritten. In other words, as the SSD is used more and more over time, the performance decrease disappears naturally. For those who want to solve the issue quickly, this software restores the read performance by rewriting the old data. The time taken to complete the procedure depends on the amount of data stored.
To summarize an article on PC Perspective, cell voltages in flash memory shift over time, and controllers are designed to correct and adjust voltage thresholds as it sees errors. The EVO wasn't doing that but instead trying to perform error correction on all data when its cells drifted far enough to the default voltage threshold.
This post was edited on 10/15/14 at 10:30 am
Posted on 10/24/14 at 11:39 pm to ILikeLSUToo
Finally just getting back to this thread. I went to this site
Samsung
to look and they have a version 1.1 now. I guess I should use the newer, right?
Thanks for posting link either way.
Samsung
to look and they have a version 1.1 now. I guess I should use the newer, right?
Thanks for posting link either way.
This post was edited on 10/24/14 at 11:40 pm
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