Storage Solutions Samsung 840 120GB SSD - Low Write Speeds

kunallkw

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Oct 3, 2008
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Hey Guys,

Yet another SSD optimization/installation thread.

So I've been using this SSD for close to 2 full years now - and I bought this used but not too old back then.

I recently came across the benchmarks for this particular drive and wanted to check my drive's performance against the marketed / other user actual results.

To my shock! I get decent Read speeds (installed the Samsung Magician FW upgrade) around 490MB/s but I see terrible write speeds @ around 100MB/s which should be around the same as Read speeds.

Based on whatever troubleshooting I could get from the interwebs - I've confirmed the following -

1 - the drive is connected to SATA 3.0 and running in AHCI Mode, using a 6GB/s SATA Cable
2 - installed the fw upgrade after Samsung released they had a bug.

To inform you I have partitioned the drive for 90% OS , 10% essential apps; Also the OS drive is 10% empty, so its nearly full.

Although I don't wish to harness the entire 500MB/s write speeds - but I just want the drive to work optimally for what I bought. Essentially to boot faster - I'm not sure if the write speeds are important for that, as the read speeds are more or less near the optimal rates.

Any help will be highly appreciated. Also let me know if I should attach screens of my Bench results.

thanks.

Kunal.
 

vishalrao

Global Moral Police
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What OS are you using and what perf tool is telling you the speeds?

It could very well be due to SSD being nearly full (and "wear-leveling" algorithm is slowing it down) - try leaving your system idle for a few hours to let TRIM do it's stuff (assuming this model has it)?
 

kunallkw

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I'm on Windows 10 and I do think this model supports TRIM

I'm using AS SSD - one I saw on that random youtube video - here's a screenshot.



And here's a screen from Samsung's own utility -





How much would you say should be the ideal free space to check bench results ?

On double thoughts - the utilities don't mention it as 840 "EVO" - should it say that it's EVO, if it's not EVO I think the write speeds are capped at 130MB/s - What do you think?
 
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Powersurge

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All 840 EVOs and 840's were affected with the low write speed bug, and there was quite an uproar about this earlier.
Samsung released two firmware fixes and a special version of magician to go with the newer firmware.

Take a look at these videos, and do a firmware update after. The current firmware is EXT0DB6Q as per samsungs site

EDIT: Here is the article you should read, as the second firmware along with the special edition of Magician (Where you are required to perform an Advanced Performance Optimization, which is not TRIM, it actually rewrites ALL the data on your SSD) finally fixed the issue.



 
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kunallkw

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Thanks for sharing this. I'll give this a try regardless. Till now I've just installed the Samsung Magician and done the FW upgrade. I think I need the dedicated tool to do the optimization steps.

But my question still remains - all of these articles and troubleshootings revolve around Read Speeds, while my issue is with the Write Speeds. Guess I'll only be able to figure out once I do it via the other tool.

Edit --

Just realised the dedicated tool doesn't exist anymore and is a part of the Samsung Magician itself. The articles are from last year and speaks about Magician 4.6, while the current ver. is 4.9
 
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Lincon_WD

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Sep 12, 2014
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Hi kunallkw,
I'd say, it's nearly full and there's little space for over provisioning (caching).
I'd test the health of the drive to ensure there are no S.M.A.R.T. errors on it that would prevent it from performing at full speeds.
Also, I'd suggest that OP frees some space (20GB or so) and then runs the benchmarks again and see if there's any difference.
Testing the drive with another cable, another SATA port and possibly on another computer again with a SATAIII bus is a pretty good idea as this could narrow things down to either the SSD or to the system itself.
But if after all of this the drive still has those low write speeds I'd consider the SSD to simply be either defective or to have suffered from a defective controller and contact the manufacturer.
Hope it helps.
 
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Crazy_Eddy

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DXT0AB0Q firmware implies you have the vanilla 840, not the Evo version.
Sequential write speeds for the 120GB 840 are indeed rated at a max of 130MB/s. (Even the 120GB 840 Evo had a rated max seq write speed of 410MB/s only as long as the turbowrite cache was not full; after that it too drops to around 130MB/s.)

You just don't have enough free space to see the max speed. And as you have noted, the 840 TLC bug affected read speeds. Run performance optimisation - it will force TRIM the drive. But otherwise, it appears your write speeds are as expected.
 

kunallkw

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Oct 3, 2008
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I think you are right, here are the benchmarks again after the - optimization step that was to be done post the FW upgrade.

I see that there is a nearly 40MB/s improvement in write speeds. Safe to assume the drive is performing optimally.



Thanks for the help guys appreciate!