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Samsung 850 EVO writes at 0.8 MB/s. Anyone else encounter this problem?

Eug

Eug

Lifer
I've been having slow writes with my Samsung on big transfers. I noticed with the Black Magic disk test on the Mac it'd start out at 400 MB/s and then drop to about 20 MB/s.

So I transferred it over to my PC and updated the firmware to EMT02B6Q. Now it writes at 0.8 MB/s or less. Samsung Magician says its status is good.

Anyone encounter this issue? If this means it's dead, that would be my second Samsung death out of 4.

Samsung 840: Died with a 1 GB total drive size. Got a replacement, but replacement running fine.
Samsung 850 EVO 250: Fine (1.6 TB written)
Samsung 850 EVO 500: Drive described above (4.5 TB written)
 
Drive is very cool.

If this is indeed related to TRIM, could I just let it sit idle all night to allow it to garbage collect?
 
Azuma Hazuki said:
Just in case, back everything up ASAP. I love SSDs but when they fail they fail hard.
Click to expand...
Drive is empty right now actually.

I have the weirdest bon... err... backup right now. I have two iMacs side by side right now, and one is a clone of the other from a couple of days ago.
 
Well, whaddya know...

I just let the drive sit empty and idle but powered up for several hours. And then I get this:

DiskSpeedTest_Samsung850EVO_zpsbhzk7isg.png


It would seem it is indeed TRIM related, because the results seem to mirror this article:

SSD in USB 3.0 enclosure

After a secure erase, the performance is decent:

USBI-HDT-Write-SecE.png


However, over time, the performance degrades to abysmal:

USBI-HDT-Write-TRIMDirty1.png


So, what drives would you recommend for external SSD storage?
 
Eug said:
I've been having slow writes with my Samsung on big transfers. I noticed with the Black Magic disk test on the Mac it'd start out at 400 MB/s and then drop to about 20 MB/s.

So I transferred it over to my PC and updated the firmware to EMT02B6Q. Now it writes at 0.8 MB/s or less. Samsung Magician says its status is good.

Anyone encounter this issue? If this means it's dead, that would be my second Samsung death out of 4.

Samsung 840: Died with a 1 GB total drive size. Got a replacement, but replacement running fine.
Samsung 850 EVO 250: Fine (1.6 TB written)
Samsung 850 EVO 500: Drive described above (4.5 TB written)
Click to expand...

Maybe.
I have two M.2 drives in USB enclosures like you but can't remember them ever having write speeds that low.
However I've also encountered an issue with some drives also in USB enclosures where write speeds dropped to around 20MB/s (and the WA could go way up).
This was not actually when they were really full but instead was after removing the folders on them (which ironically was done in order to keep the WA low).
Didn't really test thoroughly however how well they recovered if they were allowed to idle long enough.

Have seen this with both Marvell and Samsung controllers (though I think there may have been at least one Marvell controller that did not suffer from the same issue).
The controller in the Trion 100 (modified Phison S10 basically) seemed to manage it pretty well but that doesn't necessarily mean that other drives using the same controller will be free of it as well.
Plus I don't think that there's another drive besides the Patriot Ignite that is both M.2 and uses the Phison S10.


Eug said:
Well, whaddya know...

I just let the drive sit empty and idle but powered up for several hours. And then I get this:

DiskSpeedTest_Samsung850EVO_zpsbhzk7isg.png


It would seem it is indeed TRIM related, because the results seem to mirror this article:

SSD in USB 3.0 enclosure

After a secure erase, the performance is decent:

USBI-HDT-Write-SecE.png


However, over time, the performance degrades to abysmal:

USBI-HDT-Write-TRIMDirty1.png


So, what drives would you recommend for external SSD storage?
Click to expand...

If it's kind of the same issue that some of my drives had then going with a fast drive may not help because I've seen an 850 Pro go down to around 20MB/s and its WA shot through the roof.
Nor am I certain of which drives that will not be affected, aside from the Patriot Ignite, maybe drives using MLC combined with a Silicon Motion controller will do better (haven't had the opportunity to see if a drive with a Silicon Motion controller will have similar issues though).

What I would recommend is probably to try to find out what causes this since I haven't seen it with my drives and/or overprovisioning the drive so it has enough spare area to play around with.
 
For external SSD storage, I'd recommend a small NAS rather than a USB3 enclosure. USB is too flaky for that kind of usage IMO.
 
i had a 1TB sandisk connected externally for a while (in a normal drive dock) and windows saw it as an SSD (in defrag) and sandisks own tool let me trim it also. (set it to once a week and never had probs)

i now have a 500GB ADATA one which windows sees as a hard disk and ADATAs software doesn't see the drive. sees my samsung and sandisk SSDs mind. guess it's down to the controller used

guess i'll see if the performance on that drops over a few weeks
 
XavierMace said:
For external SSD storage, I'd recommend a small NAS rather than a USB3 enclosure. USB is too flaky for that kind of usage IMO.
Click to expand...
I have a NAS. This is mainly for backups and for beta OS installs, etc.

As for flakiness, I've found that most of the flakiness disappears if you get one with external power. Even applies for 2.5" drives. I had a problem with a FW/800 USB3 enclosure with an SSD running off bus power, but as soon as I plugged in a power adapter, all the problems disappeared. Ran it for 1.5 years as a primary boot drive actually. Main problem was lack of TRIM.

I've noticed this type of behaviour on several different enclosures with several different computers, so now I usually just buy enclosures that can support external power, even if it is a 2.5" enclosure. In contrast, most of the dedicated third party external drives from the big companies I've tried are fine on bus power alone. I guess they design these things to account for potential fluctuations in bus power.
 
Charlie22911 said:
OP, does your external enclosure support UASP?
Click to expand...
Not sure. The current model apparently does, but I got mine a couple of years ago. This is the enclosure:

https://eshop.macsales.com/item/OWC/MEPMU3F8K/

owc_mercuryalpro_mini.jpg


However, I can get 430 MB/s out of it with that SSD. I didn't think you could get more than 400 with plain non-UASP 5 Gbps USB.

Same goes for my USB 3 dock. No mention of UASP in the specs, but I can get 430 MB/s out of it, and I saw review online that claims the dock supports UASP.

 
Last edited:
Eug said:
Not sure. The current model apparently does, but I got mine a couple of years ago. This is the enclosure:

https://eshop.macsales.com/item/OWC/MEPMU3F8K/

owc_mercuryalpro_mini.jpg


However, I can get 430 MB/s out of it with that SSD. I didn't think you could get more than 400 with plain non-UASP 5 Gbps USB.

Same goes for my USB 3 dock. No mention of UASP in the specs, but I can get 430 MB/s out of it, and I saw review online that claims the dock supports UASP.

Click to expand...

Just spitballing here, but I am curious if the enclosure is passing SMART data and TRIM to the OS. If not, I can help but wonder if the drive controller isn't being overwhelmed with garbage collection?
 
in my case I've just ran a batch file on my desktop (run as admin) and it seems to work:

defrag d: /l /u /v
pause

anyone think of a better way of doing this?
 
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