Review Index:

Samsung 850 EVO 120GB and 500GB RAID and RAPID Review - VNAND Goes TLC

Subject: Storage
Manufacturer: Samsung

Introduction, Specifications and Packaging

Mid last year, Samsung introduced the 840 EVO. This was their evolutionary step from the 840 Pro, which had launched a year prior. While the Pro was a performance MLC SSD, the EVO was TLC, and for most typical proved just as speedy. The reason for this was Samsung’s inclusion of a small SLC cache on each TLC die. Dubbed TurboWrite, this write-back cache gave the EVO the best write performance of any TLC-based SSD on the market. Samsung had also introduced a DRAM cache based RAPID mode - included with their Magician value added software solution. The EVO was among the top selling SSDs since its launch, despite a small hiccup quickly corrected by Samsung.

Fast forward to June of this year where we saw the 850 Pro. Having tested the waters with 24-layer 3D VNAND, Samsung revises this design, increasing the layer count to 32 and reducing the die capacity from 128Gbit to 86Gbit. The smaller die capacity enables a 50% performance gain, stacked on top of the 100% write speed gain accomplished by the reduced cross talk of the 3D VNAND architecture. These changes did great things for the performance of the 850 Pro, especially in the lower capacities. While competing 120/128GB SSDs were typically limited to 150 MB/sec write speeds, the 128GB 850 Pro cruises along at over 3x that speed, nearly saturating the SATA interface. The performance might have been great, but so was the cost - 850 Pro’s have stuck around $0.70/GB since their launch, forcing budget conscious upgraders to seek competing solutions. What we needed was an 850 EVO, and now I can happily say here it is:

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As the 840 EVO was a pretty big deal, I believe the 850 EVO has an equal chance of success, so instead of going for a capacity roundup, this first piece will cover the 120GB and 500GB capacities. A surprising number of our readers run a pair of smaller capacity 840 EVOs in a RAID, so we will be testing a matched pair of 850 EVOs in RAID-0. To demonstrate the transparent performance boosting of RAPID, I’ll also run both capacities through our full test suite with RAPID mode enabled. There is lots of testing to get through, so let’s get cracking!

Read on for the full review!


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Major differences from the 840 EVO line include the lack of a 750GB model. You might also note a new MGX controller in the capacities below 1TB. Samsung told us they have optimized their controller firmware enough that the triple core MEX is only needed for the 1TB capacity. Lower models can still reach full performance with a new dual core MGX controller. This move was to push power consumption figures of the smaller capacity EVOs down even further, as evidenced by the chart below:

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Note the 15-25% reduction in active power consumption of the 120-500GB models - due to the elimination of one of the active controller cores.


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The usual Samsung packaging. If it ain't broke, don't fix it.

Video News

December 8, 2014 | 10:49 AM - Posted by Anonymous (not verified)

Nice review although your bar charts are so hard to read my eyes glaze over when i see one. I wish they'd drop the 120GB model and move the industry forward to a 256gb standard entry point.

December 8, 2014 | 10:58 AM - Posted by Anonymous (not verified)

I wish they'd drop the 120GB model and move the industry forward to a 256gb standard entry point.

Within the consumer PC market, yes, specifically laptops/ultrabooks the entry point should be at least 240/250/256GBs.

For the DIY crowd, I would argue that 120GB or hell even 64GB drives are still a great option for different builds when considering price. For HTPC's for example, a 64GB drive is damn near perfect - low space and speed requirements. I would not want to shell out $150+ for a 2xxGB drive when I could get a 64GB for <$80.

December 8, 2014 | 11:53 AM - Posted by collie


March 28, 2015 | 02:55 AM - Posted by Christian Henriquez (not verified)

I agree with you if the consumer only has one bay but on the other hand offering a lower capacity drive is more cost effective and beneficial for consumers looking to either do a striped raid or simply use the SSD as an OS drive. This option is enticing for many consumers and would likely be a deal breaker for some if the lower capacity option did not exist. Therefore Samsung must continue to offer these drives to ensure that they don't lose potential customers. However, I do agree with your idea of industry advancement and in my opinion Samsung is well on track with doing so, they have given better performance while dramatically reducing the price of the drive which will stimulate the SSD market by envoking competition and in return, slowly but surely, consumers will enjoy the better performance and decreasing costs.

December 8, 2014 | 11:43 AM - Posted by Allyn Malventano

What about the bar charts makes them difficult for you? Would it help if the bars were solid?

December 8, 2014 | 12:08 PM - Posted by John H (not verified)

For me either a white background (dark blue is a bad choice for colored lines, even though I really like the PCPer scheme) or solid bars would help. I can't speak to the OP.

Don't forget about 5-10% of the population are color blind, so you could have a lot of readers that would benefit from more contrast of the white background..

December 8, 2014 | 12:19 PM - Posted by cyberwire

sometimes the colors are too close to tell apart!! There's 3 different blue lines with a blue background to boot.

December 8, 2014 | 12:55 PM - Posted by PJeff (not verified)

Allyn, It would help to have a drop down menu to select other SSDs to compare to the one(s) you're reviewing. This way, we can see the bars/graphs a lot easier without a dozen other lines and colors getting in the way. As you guys review more drives, the graphs are going to get harder and harder to read.

December 8, 2014 | 01:31 PM - Posted by Anonymous (not verified)

Solid would help, and if you could have the drives you're reviewing a different set of colors than the rest that would help distinguish them.

February 4, 2015 | 10:14 PM - Posted by Mr_Scary (not verified)

Can these use the Sata Express 10Gbp/s ports like found the ASUS X99 Deluxe??
And can you use RAID0 on the 2 Sata Express ports?
The do have 2 separate controllers on-board.

I also had some trouble with the charts, some of the colors are the same to me.

I think the information should be inside the bar, that way it won't matter if the bars are all the same color.
but colors still help for quick identification.

I did have to count downward to make sure I was looking at the correct bar.

the charts do look really neat, and organized though.

BTW. this info. was very helpful.
I have been using RAID0 with 4 WD Blacks for several years.
So RAID is really great, people have some illusion that more drives have a higher failure rate, but I say how is that possible whane the work load gets split by each drive, the more drives, the less they get used. fewer spin cycles
But that's mech drives...

Another thing people get wrong is: if a drive fails, all your data is lost with a RAID0, Not true if you back up your drive regularly. And also if you have a single drive that fails, you still lose the data. Right?

Been using RAID 0 for 6 years. 0% failure rate.

Can't wait to RAID0 2 850 EVO 500GB on a ASUS X99 Deluxe.

December 8, 2014 | 11:53 AM - Posted by collie

Personaly I love the 120gb C:, call me crazy but I like to be able to format my c: often (1-3 times a year) and get a fresh clean install. keeping my c: tiny help prevent putting anything important on there. Would love to get a big ssd for my d: drive tho, keep games on that and media on the hdd, that would be the perfect storage setup I think.

December 8, 2014 | 01:29 PM - Posted by Anonymous (not verified)

Fair enough, i didn't consider those types of scenarios.

December 8, 2014 | 11:07 PM - Posted by Anonymous (not verified)

ok collie, I'll call ya crazy :p

I'm using 98 GB of my C drive. That's a bit too close to the 128GB limit for my comfort!

I specify my C drive, as I do have a 447 GB D drive for games. All other programs are on C drive.

I do a clean install maybe every year-ish (and i'm sure I'm overdue), and I don't miss the excuse of "my 60 GB SSD is full...again" one bit!

December 8, 2014 | 02:42 PM - Posted by Fasic (not verified)

Right now, on my notebook, i have 640GB HDD, with 8 partitions(3 OS's) C:(win7) with just 100 and it is more then i need...with so much crap on Disk that i don't 120 with normal R/W speeds would be good for me...but 240 is sweet spot because right now my games are on other partition, with 240 i would go all on C: or better one, with 120(fast 1) + 120, C: = 120 and games 120 is just yea there is people that like 120Gig model...

#PcPer fix graphs please...

December 8, 2014 | 12:15 PM - Posted by Greg (not verified)

How do the Samsung drives perform in situations where TRIM is not supported?

December 8, 2014 | 03:04 PM - Posted by Allyn Malventano

They should be at least decent due to their very good performance consistency (also good for RAID performance in general). If your use is RAID-5 (which is mostly incompatible with TRIM), I'd go with a slight overprovisioning to help keep the long term random performance on the high end.

I will say that even if the TLC area gets fragmented over time, most of your consumer-level writes are going to go to that SLC cache, so any speed reductions would be mostly transparent to the end user.

December 8, 2014 | 12:23 PM - Posted by Rick (not verified)

Hey Al

Go you go into detail on how you configure raid 0 for ssds to get the best performance. That would be a great and useful write up.


December 8, 2014 | 02:59 PM - Posted by Allyn Malventano

For this piece I went as dead simple as possible, using Intel's defaults (which turned out to be 16k stripe size for this capacity). So long as you don't go too large on stripes, you should be ok in a RAID-0. Smaller stripes increase overhead, large stripes reduce the effective parallelism you achieve during smaller accesses. It's a balancing act really, and I would only tweak the defaults based on very specific circumstances / usage scenarios.

More importantly from these results, the benefits of disabling write cache buffer flushing and enabling the write back caching is far outweighed by the potential consequences of losing data or corrupting the file system should a power loss / BSOD occur during a heavy write workload. If you have quick SSDs, don't bother with the added caching, for your own protection.

December 8, 2014 | 02:01 PM - Posted by Anonymous (not verified)

Incredibly disappointing, especially for something that showed as much promise as vnand.
I was watching some old podcasts recently and Allyn was talking about rumors that the 840 EVO would launch around $0.50/GB, and now, several years later, the 850 EVO launches at $0.50-$0.83/GB. It's looking increasingly like SSDs (or at least nand-based ones) are not the future of storage; the prices simply are not coming down. What's the point of fast storage if it's too small to store anything? $0.50+/GB is frankly a ridiculous price to pay for storage in 2014.
At least the warranty is 5 years, finally matching that of supposedly less reliable hard drives.

December 8, 2014 | 02:34 PM - Posted by pdjblum


December 8, 2014 | 02:28 PM - Posted by Shambles (not verified)

At this point I think I may simply wait for PCIE based SSDs. With all these developments (TLC, 3D NAND) that may have had some performance implications but ultimately was supposed to bring prices down by making the flash cheaper to product simply have no brought said prices down. While the 850 looks solid why anyone would buy these drives over their slightly slower but significantly cheaper rivals (Hello MX100) is beyond me.

December 8, 2014 | 02:45 PM - Posted by razor512

How does the 850 evo compare to the 840 pro?

For example, the 128GB 850 evo, cost $10 more than the 128GB 840pro, what would provide a better experience with the user?

December 8, 2014 | 03:01 PM - Posted by Allyn Malventano

The 850 EVO outperforms the 840 Pro on everything but uncached writes on the smaller capacities. We're talking a newer generation controller and flash - it's basically a completely new device, with the only commonality being the SATA 6Gb/sec bandwidth limit.

December 8, 2014 | 03:44 PM - Posted by pdjblum

The 840pro uses mlc rather than tlc, is a great performer, and lasts forever as shown in the TechReport's ongoing SSD longevity test. To me, TLC is a downgrade, and the better performance of the newer drive, especially since it costs more (oh yeah, tlc is cheaper, right) might not be worth the trade off of quality.

December 8, 2014 | 08:06 PM - Posted by razor512

hopefully someone does a write endurance test on it. I consider an SSD to be at the time for replacement as soon as cells start to fail (regardless of the reserves). Due to wear leveling, when a few cells start to die, you can bet that all of them are close to death and the chance of uncorrectable errors and corruption will be higher.

When I go for an SSD, I want the write endurance to be at a level where I will not have to think about it regardless of the application I run, or how hard it hits a drive that it is suing as a scratch disk.

With the 840 evo, the 240GB model reached the failure state at about 90Tb of writes, (bad when I am doing close to 50TB per year in writes to the drive). (This is with me not even copying source video content to the SSD, and just the caching and other writes that I do to the drive from running photoshop, adobe premiere pro, aftereffects, maya, and doing some gaming, is enough to push close to 50TB per year).

I ended up buying an 256GB 850 pro, mainly for the write endurance

My previous drive was a 120GB sandisk (sata 2) which I had put over 150TB of writes onto in less than 3 years (I think it used flash in the 30nm range. No flash failures were recorded, and it is now a secondary drive for my steam games.

PS, sorry for the typo in the original post, I meant to say 120GB.

December 8, 2014 | 04:01 PM - Posted by Marko (not verified)

I have two 840 Pro's (1 in each of 2 systems) for the longest time, I had RAPID enabled. Then I disabled RAPID because Passmark's pc benchmarking software flagged RAPID as skewing the results. I literally noticed no difference between RAPID being on or off. Just figured it was marketing hype.

Anybody else notice this?

Specs (both systems)

i7 4790k @4.6Ghz (watercooled) ASUS Hero VII mobo, 16Gb Corsair Dominator Platinum 2133mhz, Corsair 1200i PSU, 2x GTX 980 SLI, 1 Samsung 840 Pro 256Gb SSD, 1 WD 6TB storage drive

December 8, 2014 | 08:05 PM - Posted by razor512

I tried rapid and it actually seems to make things slower. It seems to lower response times while offering no benefit to things like game load times. It also slows the system boot speeds and only seems to positively impact some storage benchmarks and nothing else.

They would have been better off making it into a program that allows you to simply create a ram disk that can be linked to a user selected file, folder, or set of files and folders that it would automatically sync. (e.g., try running left 4 dead 2 on a RAM disk; the load times are awesome)

December 8, 2014 | 08:20 PM - Posted by Anonymous (not verified)

Agreed, I just enabled rapid on my new 850 pro and i can't really tell the difference either, although like you said benchmarks are off the charts. I think i got like 4k in AS SSD or something crazy.

Figured extracting archives and file copying would receive a boost, but there isn't one as far as i can tell. Applications start up around the same speed as they did before as well...

December 8, 2014 | 06:04 PM - Posted by dtkflex

Based on your data is there any benefit to enabling RAPID on larger drives like the 1TB 850 Pro?
Or is it better to leave that feature off for those size drives?

December 10, 2014 | 09:21 PM - Posted by Anonymous (not verified)

Allyn, i just updaded my samsung majician to ver. 4.5, now when i enable rapid mode, i get BSOD, and the computer wont boot up, i have to go to a restore point, then download the 4.5 version and run without RAPID MODE..have you come accross this running 850pro 256GB....i had ver. 4.4 and it was running fine with RAPID MODE it wont work....

thanks for you help

October 29, 2015 | 09:38 PM - Posted by MACSARE4US (not verified)

I LOVE THE 120GB DRIVES, I HAVE 8 and 16 IN A RAID 10, ON A RR WITH SFF-8087 CABLES GOING STRAIGHT TO THE STARTECH 4X CANS,ON PCIe2X8 lanes sequential writes and reads are >98% of spec, 6.8TBs on a 16lane ROC

October 31, 2015 | 12:39 AM - Posted by MACSARE4US (not verified)

performance numbers raid 0,
sorry, Raid 10 writes are at 50% eventhough they shouldn't be old school thinking,raid 10 reads are really great (from 2 sets) near mfg spec
its a new age, ROC isn't a necessity if you have one of the hottest 6 core processors, or 12cores and countless threads, amazingly the software raid cards- HPoint RR 2722 still run great on a core duo QX9850alchol,nanosilver cooled running @ 3.8 refrigerated (Freezer system- BLOWS -18℉ offline, we still keep sitting around in a 32 bay case w/2-2722 for near 3 years a FXO file sever with asus P5Q-E WITH 2 RR2722 now w/ 4 - ROCKET EJx40 - TOTAL 64 DRIVE Potential SATAII EJ240, and SATA3 using EJ340 AND 10 MORE ON MB POSSIBLE W/ ESATA
BUT I Run only 8 ssd,or i should say 4 to a 8087 SAS port, unless I was processing CCard transactions iops aren't that important to me , oops don't waste my time ,big sequential xfers from NOL do, so when Ihave to move to a WORKST I TRY TO DO 2 DAYS WORTH drawing a goodbye sometimes from SCSI, Still keep 7 Micropolis 4GB 5¼" FULL Height, had 56 online 25 yrs ago, wow, just wanted 4MB/S BACK THEN WITH 30K$ workstation
GOOD LuCK TO ALL, i started in Fortran on 13' floppies AND SOLDERING IN 1960, SEEYA EFI!

March 27, 2016 | 05:50 AM - Posted by LightspeeD

i have 3x 500Gb Evo's in RAID 0. Read = 1570 mb/sec. Writes = 1520 mb/sec.

system is 6700k @4.5Ghz stock volts. TridentZ's. Windows 10 home.

April 26, 2016 | 09:21 PM - Posted by Anonymous (not verified)

4*850evo@500gb in Raid0 on HP P420:
2.1GB/s read, 1.7GB/s write

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