Samsung ssd 840 evo test: 120GB, 250GB, 500GB, 750GB & 1TB Models Tested

Introduction & PricingInside the Drives & Spare AreaEndurance: Not a Problem Even at 19nmTurboWrite: MLC Performance on a TLC DriveRAPID: PCIe-like Performance from a SATA SSDPerformance Consistency & Testing TRIMAnandTech Storage Bench 2013Random & Sequential PerformancePerformance vs. Transfer SizeAnandTech Storage Bench 2011Power ConsumptionFinal Words

I’m continually amazed by Samsung’s rise to power in the SSD space. If you compare their market dominating products today to what we were reviewing from Samsung just a few years ago you’d assume they came from a different company. The past three generations of Samsung consumer SSDs have been good, but if you focus exclusively on the past two generations (830/840) they’ve been really good.

Last year Samsung bifurcated its consumer SSD lineup by intoducing the 840 Pro in addition to the vanilla 840. We’d seen other companies explore a similar strategy, but usually by playing with synchronous vs asynchronous NAND or sometimes just using different NAND suppliers between lines. Samsung used NAND to differentiate the two but went even more extreme. The non-Pro version of the 840 was the first large scale consumer SSD made with 3-bit-per-cell MLC NAND, more commonly known as TLC (triple-level-cell) NAND. Companies had toyed with the idea of going TLC well before the 840’s release but were usually stopped either by economic or endurance realities. The 840 changed all of that. Although it didn’t come with tremendous cost savings initially, over time the Samsung SSD 840 proved to be one of the better values on the market — you’d just have to get over the worry of wearing out TLC NAND.

Despite having a far more limited lifespan compared to its 2bpc MLC brethren, the TLC NAND Samsung used in its 840 turned out to be quite reliable. Even our own aggressive estimates pegged typical client write endurance on the 840 at more than 11 years for the 128GB model.

Samsung 19nm TLC NAND

We haven’t seen Samsung’s love of TLC embraced by other manufacturers. The most significant contrast actually comes from Micron, another NAND supplier turned SSD manufacturer, and its M500. Relying on 2bpc MLC NAND, the M500 gets its cost down by using a combination of large page/block sizes (to reduce overall die area) as well as aggressively embracing the latest NAND manufacturing processes (in this case 20nm). That’s always been the Intel/Micron way — spend all of your time getting to the next process node quickly, and drive down cost that way rather than going TLC. The benefit of the TLC approach is the potential for even more cost reduction, but the downside is it usually takes a while to get production to yield high enough endurance TLC to make it viable for use in SSDs. The question of which is quicker is pretty simple to answer. If we look at the 25nm and 20nm generations from IMFT, the manufacturer was able to get down to new process nodes quicker than Samsung could ship TLC in volume.

The discussion then shifts to whether or not TLC makes sense at that point, or if you’d be better off just transitioning to the next process node on MLC. Samsung clearly believes its mainstream TLC/high-end MLC split makes a lot of sense, and seeing how the 840 turned out last time I tend to agree. It’s not the only solution, but given how supply constrained everyone is on the latest NAND processes this generation — any good solution to get more die per wafer is going to be well received. Samsung doesn’t disclose die areas of its NAND, so we unfortunately can’t tell just how much more area efficient its TLC approach is compared to IMFT’s 128Gb/16K page area efficient 20nm MLC NAND.

As with any other business in the tech industry, it turns out that a regular, predictable release cadence is a great way to build marketshare. Here we are, around 9 months after the release of the Samsung SSD 840 and we have its first successor: the 840 EVO.

As its name implies, Samsung’s SSD 840 EVO is an evolution over last year’s SSD 840. The EVO still uses 3-bit-per-cell TLC NAND, but it moves to a smaller process geometry. Samsung calls its latest NAND process 10nm-class or 1x-nm, which can refer to feature sizes anywhere from 10nm to 19nm but we’ve also heard it referred to as 19nm TLC. The new 19nm TLC is available in capacities of up to 128Gbit per die, like IMFT’s latest 20nm MLC process. Unlike IMFT’s 128Gb offering, Samsung remains on a 8KB page size even with this latest generation of NAND. The number of pages per block is also more like IMFT’s previous 64Gbit 20nm MLC at 256:

IMFT vs. Samsung NAND Comparison
	IMFT 20nm MLC	IMFT 20nm MLC	Samsung 19nm TLC	Samsung 21nm TLC	Samsung 21nm MLC
Bits per Cell	2	2	3	3	2
Single Die Max Capacity	64Gbit	128Gbit	128Gbit	128Gbit	64Gbit
Page Size	8KB	16KB	8KB	8KB	8KB
Pages per Block	256	512	256	192	128
Read Page (max)	100 µs	115 µs	?	?	?
Program Page (typical)	1300 µs	1600 µs	?	?	?
Erase Block (typical)	3 ms	3. 8 ms	?	?	?
Die Size	118mm2	202mm2	?	?	?
Gbit per mm2	0.542	0.634	?	?	?
Rated Program/Erase Cycles	3000	3000	1000 — 3000	1000 — 3000	3000 (?)

The high level specs, at least those Samsung gives us, points to an unwillingness to sacrifice latency even further in order to shrink die area. The decision makes sense since TLC is already expected to have 50% longer program times than 2bpc MLC. IMFT on the other hand has some latency to give up with its MLC NAND, which is why we see the move to 2x larger page and block sizes with its 128Gbit NAND die. Ultimately that’s going to be the comparison that’s the most interesting — how Samsung’s SSD 840 EVO with its 19nm TLC NAND stacks up to Crucial’s M500, the first implementation of IMFT’s 128Gbit 20nm MLC NAND.

Modern Features

Along with the NAND update, the EVO also sees a pretty significant controller upgrade. The underlying architecture hasn’t changed, Samsung’s MEX controller is still based on the same triple-core Cortex R4 design as the previous generation MDX controller. The cores now run at 400MHz compared to 300MHz previously, which helps enable some of the higher performance on the EVO. The MEX controller also sees an update to SATA 3.1, something we first saw with SanDisk’s Extreme II. SATA 3. 1 brings a number of features, one of the most interesting being support for queued TRIM commands.

The EVO boasts hardware AES-256 encryption, and has its PSID printed on each drive label like Crucial’s M500. In the event that you set and lose the drive’s encryption key, you can use the PSID to unlock the drive (although all data will be lost). At launch the EVO doesn’t support TCG Opal and thus Microsoft’s eDrive spec, however Samsung tells us that a firmware update scheduled for September will enable both of these things — again bringing the EVO to encryption feature parity with Crucial’s M500.

As one of the world’s prominent DRAM makers, it’s no surprise to find a ton of DRAM used to cache the firmware and indirection table on the EVO. DRAM size scales with capacity, although Samsung tosses a bit more than is necessary at a couple capacity points (e.g. 250GB).

The move to 19nm 128Gbit TLC NAND die paves the way for some very large drive capacities. Similar to Crucial’s M500, the 840 EVO is offered in configurations of up to 1TB.

Samsung SSD 840 EVO Specifications
	120GB	250GB	500GB	750GB	1TB
Controller, Interface	Samsung MEX, SATA 3.1
NAND	Samsung 19nm 3bpc TLC Toggle DDR 2.0 NAND
Form Factor	2. 5″ 7mm
Max Sequential Read	540MB/s
Max Sequential Write	410MB/s	520MB/s
Max 4KB Random Read	94K IOPS	97K IOPS	98K IOPS
Max 4KB Random Write	35K IOPS	66K IOPS	90K IOPS
Encryption	AES-256 FDE, PSID printed on SSD label
Warranty	3 years

I’ll get to the dissection of performance specs momentarily, but you’ll notice some very high peak random and sequential performance out of these mainstream drives. The peak performance improvement over last year’s 840 is beyond significant. The keyword there is peak of course.

Pricing

Samsung expects the 840 EVO to be available in the channel at the beginning of August. What we have in the table below are suggested MSRPs, which as long as supply isn’t limited usually end up being higher than street prices:

SSD Pricing Comparison — 7/24/2013
	120/128GB	240/250/256GB	480/500/512GB	750GB	960GB/1TB
Crucial M500	$120. 99	$193.56	$387.27		$599.99
Intel SSD 335		$219.99
Samsung SSD 840	$98.44	$168.77	$328.77
Samsung SSD 840 EVO	$109. 99	$189.99	$369.99	$529.99	$649.99
Samsung SSD 840 Pro	$133.49	$230.95	$458.77
SanDisk Extreme II	$129.99	$229.77	$449.99
SanDisk Ultra Plus	$96. 85	$174.29
OCZ Vertex 450	$129.99	$246.84

Prices are a bit higher than the outgoing Samsung SSD 840, which makes sense since we’re looking at the beginning of the cost curve of a new process node. Crucial’s highly sought after $600 960GB M500 seems finally back in stock just in time for the EVO to go head to head with it. Samsung is expecting roughly a $50 premium for the 1TB EVO over the Crucial solution, but over time I’d expect that gap to shrink down to nothing (or in favor of Samsung). The EVO is considerably more affordable than Samsung’s 840 Pro, and the higher capcacity points are at particularly tempting prices.

Inside the Drives & Spare Area
Introduction & PricingInside the Drives & Spare AreaEndurance: Not a Problem Even at 19nmTurboWrite: MLC Performance on a TLC DriveRAPID: PCIe-like Performance from a SATA SSDPerformance Consistency & Testing TRIMAnandTech Storage Bench 2013Random & Sequential PerformancePerformance vs. Transfer SizeAnandTech Storage Bench 2011Power ConsumptionFinal Words

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Samsung 840 EVO SSD: Tested At 120, 250, 500, And 1000 GB

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Imagine the following conversation between two Samsung executives:

«What are we going to do tonight?”. Suit number two replies, “The same thing we do every night. Try and take over the world.”

Samsung’s previous-gen 470 and 830 SSDs

«Yeah, okay. How?»

«Branded memory products.»

«Memory products? I’m sold. Let’s do it.»

And so that’s what the company is doing. In an era where everything needs DRAM and NAND flash, the fabricator is king. If you’re the largest fabricator…well, you’re halfway there. This is a target-rich environment, too. With SSD shipments still accelerating, it seems like any company could stay solvent selling solid-state storage. But that’s just not the case. This market is dominated by the companies producing the NAND, and Samsung’s biggest. 

Working its way to the top of the SSD space didn’t happen overnight, though. It took successive products offering strong performance, enough time to reassure folks that the drives are reliable, and ginormous quantities of flash.

Samsung’s first drives were a lot like other early SSDs. I call them proto-SSDs; they’re the missing link between old-school flash-based storage and more modern architectures, which we were introduced to roughly around the time Intel launched its X25-M and -E. Before then, SSDs were sequential transfer machines, lacking a focus on the small-block random access agility we take for granted today. Some lacked native command queuing, the TRIM command was still a twinkle on the horizon, and many models employed the IDE interface with a SATA bridge. Samsung didn’t join the new-school SSD business until 2010, despite its presence from the beginning, selling Jurassic-period drives to OEMs.

Once the company really started swinging its scepter at the desktop SSD market, its ascension was swift. The 470 was really Samsung’s first foray into the über-competitive consumer space. It was fine in its own right, but was overshadowed by the flood of SandForce-based models (not to mention Intel’s efforts). Then there was the 830, which did well among press and end users alike. Versions of the 830 became some of the first 6 Gb/s SSDs shipping in laptops, most notably those from Apple. Deserving praise was doled out liberally. Samsung had the ability to develop everything in-house, and the 830 showed off the significance of that advantage even more than the 470.

A year later, the company split its consumer offerings into two separate families: the 840 Pro and 840. They’re similar in many ways, except the flagship 840 Pro sports Toggle-mode DDR flash. It’s a great product, one of the fastest we’ve tested, and enthusiasts love it. But in the grand scheme of things, it’s not as important as the 840, built from three-bit-per-cell NAND. Several companies claimed that drives with this memory technology were imminent well before the 840’s launch. However, Samsung was the first to get it done. That wasn’t the drive we were looking for, though. Absurdly low endurance ratings? Crazy high latency? No thanks. In fact, we weren’t sure why the 840 made sense at the time. Back then, capacities were increasing and prices were dropping fast on the familiar MLC-based SSDs.

Samsung’s new 840 EVO

Getting that first TLC-based drive out there wasn’t about selling drives at retail. Rather, it was about locking down the OEM sales that drive the SSD industry. Those OEMs sell a lot of volume and are super price-sensitive. Cutting a few bucks from a drive doesn’t mean a ton to you or me, but dropping the bill of materials on a popular notebook is huge for a company like Apple or Dell.

And as it turned out, the 840 wasn’t a hopeless dog, either. It didn’t die after 1000 P/E cycles, and it wasn’t particularly slow. In fact, we have a drive that went a full 3207 P/E cycles before it cratered last December. I’ve seen similar results from others, so the endurance debate may be a red herring in consumer workloads. Write performance was modest, and read speeds exceeded most two-bit-per-cell competitors.

Overall, Samsung says the drive was about increasing adoption rates, and the company’s plan seems to have worked. Representatives claim Samsung served up 2,524,699 840s already, good for an astounding 20% of the aftermarket. That means one out of every five SSDs sold through e-tailers since the launch was an 840. If that stat is true, it’s amazing. How do you top such a thing?

Samsung’s Next-Gen 840: The EVO

We’re not sure if EVO stands for evolution or nothing specific at all. Regardless, the drive’s inner workings, hidden under a new metal chassis, are definitely an improvement on the original 840 and not a ground-up redesign. To be fair, the 840 wasn’t broken, so no fix was necessary. But with a tuned controller, 19 nm NAND, and a technology that Samsung calls Turbo Write, the end result is…different.

Five 840 EVO models are launching early August in most major markets. Switching from 21 nm, 64 Gb die to 19 nm, 128 Gb die allows the EVO to double in capacity. The old 840 topped out at 500 GB; the EVO maxes out at 1 TB. That gives us a line-up with 120, 250, 500, 750, and 1000 GB options. More capacity is always a good thing, particularly since Crucial’s 960 GB M500 suffered poor availability after it launched. The 750 GB model is a little unusual, but we’re down with that, too.

Swipe to scroll horizontally

Samsung 840 EVO	120 GB	250 GB	500 GB	750 GB	1 TB
MSRP	$110	$190	$370	$530	$650
Controller	400 MHz Samsung MEX, three-core ARM Cortex-R4
NAND	19 nm Samsung Toggle-mode NAND (400 Mb/s), three-bit-per-cell
Form Factor/Interface	2. 5″, 7 mm Z-height, SATA 6Gb/s
Warranty	Three Years
Seq. Read/Write (MB/s)	540 / 410	540 / 520
Rand. 4 KB Read QD 32 (IOPS)	94,000	97,000	98,000	98,000	98,000
Rand. 4 KB Write QD 32 (IOPS)	35,000	66,000	90,000	90,000	90,000
Rand. 4 KB Read QD 1 (IOPS)	10,000	10,000	10,000	10,000	10,000
Rand. 4 KB Write QD 1 (IOPS)	33,000	33,000	33,000	33,000	33,000
Die Count	8	16	32	48	64

That’s five EVO models, stretching from 120 GB to 1 TB. And they’re shipping at the 840’s price points, too. Samsung is really proud of this, though we’d frankly like to see three-bit-per-cell NAND on a smaller process pulling prices down instead of propping them up. In time, perhaps. Likely, the company is hoping that more performance and capabilities are what you’ll focus on.

A new version of Samsung’s management software, SSD Magician, will also roll out alongside the EVO, sweetening the deal with revamped cloning functionality and a feature called RAPID, which is host-side DRAM caching that works with Windows to push storage performance beyond the limitations of a 6 Gb/s SATA interface.

Speaking of speed-ups, check out those specs. If you’re familiar with the original 840, then you see that the write performance is radically improved. How does Samsung achieve this? We’ll dig deeper on the next page.

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Test and review: Samsung SSD 840 EVO 120, 250 and 500 GB

As the name suggests, the Samsung SSD 840 EVO (lution) is a further improvement of the 840 Basic. But instead of a complete upgrade of the drives, Samsung left the 840 Pro in the high-end SSD segment, replacing only the mainstream model. The updated drive has received the latest technology and features, which should increase its attractiveness in the market. In our article, we will just talk about new features and performance.

Samsung SSDs are in a unique position in the market because they are the only manufacturer to produce all components for SSD production: controller with firmware, DRAM cache and NAND flash memory. Other manufacturers, such as Micron, usually produce only NAND memory, and the controller is purchased on the side. The advantages of own production of components are obvious. All departments of the company can closely interact with each other during development and testing, quickly solve emerging problems.

Samsung SSD 840 Series EVO with a new design — the manufacturer abandoned the orange color

Perhaps for this reason, Samsung is able to quickly release new technologies to the market. The Samsung SSD 840 Basic is almost a year old, the first TLC SSD for the consumer market, unlike MLC, can store not two, but three bits per cell, which gives a higher recording density. And a lower price level, which is important for end users.

Note: we’ve changed the test system a bit — now we’re using the latest PCMark 7, an outdated graphics card 9We have replaced the 600 GT with a more recent GTX 580. So the PCMark results are no longer consistent with those obtained in our previous tests.

The technical specifications are as follows:

Manufacturer and model MZ-7TE120BW / MZ-7TE250BW / MZ-7TE500BW
Retail price	N/A
Manufacturer website	www. samsung.com
Technical specifications
Form factor	2.5″
Capacity (manufacturer’s information)	120 / 250 / 500 GB
Capacity (after formatting)	112 / 233 / 466 GiB
Container options	120 / 250 / 500 / 750 / 1000 GB
Cache	256 / 512 / 512 MB LPDDR3
Controller	Samsung MEX
Flash memory	TLC (Toggle, 19 nm)
Reading speed (manufacturer information)	540 MB/s
Write speed (manufacturer’s information)	410 / 520 / 520 MB/s
Manufacturer’s warranty	3 years
Delivery set	3.5″ mount, SATA data cable, SATA to USB adapter (included in Kit)

<>Test and review: Samsung SSD 840 EVO 120, 250 and 500 GB
Samsung 840 EVO in detail (1)

Drive performance depends on temperature

Last fall, it became known that the Samsung 840 Evo solid state drive slows down when reading old data. Information recorded over a month ago could only be read with a performance drop, and Samsung soon released a patch with a firmware update that was intended to solve this problem. Then it was pointed out that the voltages for cells with old data were not calibrated correctly. As it turned out later, the problem still remained, and the second update should solve it, which periodically overwrites the old data in the background. Per Hansson found out that other Samsung drives with TLC NAND memory are also affected by the degradation problem.

Samsung 840 Evo are drives from 120 gigabytes to 1 «honest» terabyte, available in form factors for connecting via SATA and mSATA. Immediately after the appearance, thanks to the aggressive pricing policy and good performance, they were one of the best solid state for home use. After some time, users began to notice something strange: the data recorded several months ago could no longer be read at full speed. Sometimes the read speed dropped to 30 MB/s. But newly written data was always read at speeds up to 500 MB/s — as fast as any benchmark that writes a new block of information for the test shows. It took only a few weeks for the drop in reading speed to show. By October 2014, the discussion thread on overclock.net was over a hundred pages long.

This is how the problem appeared six months ago.

Samsung quickly acknowledged the problem and promised to release a patch. By the end of October, a special utility was released for both 2.5-inch drives (EXT0CB6Q) and drives connected via mSATA (EXT42B6Q). The program performed two simple steps:

• The disk firmware was updated. The new one took into account the inevitable shift in voltage levels that occurs in all NAND cells as they age. This effect was amplified by the number of bits stored in each cell: only one bit is stored in SLC NAND, and its two states can be easily distinguished. In MLC NAND, each cell stores two bits, and it becomes more difficult to read them, but the amount of data stored is doubled. TLC NAND requires correct calibration of eight voltage levels at once, but the amount of data increases by another one and a half times.

  According to the manufacturer, a bug crept into the algorithm that read the data, causing the old data to become more and more difficult to read. Reading speeds of old files dropped from about 500 MB/s to less than 50 MB/s — 10 times. Detecting this issue was difficult because benchmarks typically write new data and read it immediately to perform a speed test. It is easy for users to notice the problem: operating system files, installed programs and applications, documents are recorded once and used daily.

• The second step completely overwrote all data on the drive. That is why the execution speed of Performance Restoration Software directly depended on the volume of the drive and the information written to it. Since the speed drop takes about 8 weeks to manifest, it was not clear for a while whether the firmware update worked.

As it turned out later, the first attempt to remedy the situation was not successful. The problem started to reappear. Samsung started working on a new firmware version (EXT0DB6Q), but this time instead of changing the algorithms for reading old data, it was decided to put in the drives periodic overwriting of old files in the background. This solution is not elegant: NAND memory cells wear out from writing and erasing, so the life of the drive will drop. But, as the study of the Tech Report shows, a good resource is laid in modern solid state.

At the time of Hansson’s writing, the update is only available for the 2.5-inch 840 Evo, and mSATA owners will have to be patient. Also, the new firmware does not work well with the implementation of the TRIM command in the Linux family of operating systems (the firmware does not support queued TRIM, although the opposite is indicated). An important detail of the latest update is the recognition of the presence of a flaw not in the firmware of the drives, but in Samsung’s TLC NAND chips. Probably, the manufacturer cannot write such an algorithm that could take into account the aging of information in the cells, so it is proposed to overwrite them.

Samsung claims that the problem is only with the 840 Evo. But it’s not. There are other versions for embedding, for example, Samsung PM851, which falls into Dell products. On the forums, users report the same problems with reading speed. Embedded versions of Samsung drives can also be found in the Razer Blade Pro laptop and Microsoft Surface Pro 3. In the latter case, Samsung released a firmware update, but later removed it from the site without explanation.

Also potentially affected is the Samsung 845DC Evo, an enterprise version of the drive, as stated on the site, specifically built for «read-intensive applications.» 845DC Evo uses the same TLC NAND chips as 840 Evo — K90KGY8S7M-CCK0. It is likely that Samsung chooses the best components for industrial solid state drives, so it may take time for reading speed drops to show up and for heated forum discussions to start.

Finally, there is the 840 (no Evo in the name), which was the first to use TLC NAND. At the moment, a firmware update for this drive has not been released. Although the drop in reading speed is also evident here, Samsung does not acknowledge the problem. Samsung Germany previously stated that older data on the 840 is slower to read, but this was later refuted in company reports. Here is Samsung’s answer to a question from PC Per.

PC Per: Will there be a firmware update for other Samsung TLC SSDs that have also exhibited this read speed issue? If so, when and for which models will new firmware versions be released?
Samsung: This issue has only been reported for 840 Evo SSDs.

Hansson cites the data he gathered from user posts on the forums:

• 840 Evo uses TLC NAND with process 19nm, and degradation takes 8 weeks.
• Regular 840 is based on 21nm TLC NAND, needs 40 weeks to age.

Below is the drop in read speed on the 840 model. The test was performed by Hansson on a Lenovo ThinkPad T530 laptop running Windows 7. A Plextor M5M mSATA was used as the primary drive, a Samsung 840 as the secondary drive. HD Tune was set to a block size of 64 KB. An empty 40 GB is not subject to read speed degradation, so it achieves a peak performance of 375 MB / s. You can see that the first part experiences a particularly severe read speed drop — this happened due to the cloning of a regular hard drive on a Compaq laptop, and the first 13 GB contains a recovery partition. In these 13 GB, which were never overwritten, there is a noticeable peak of two empty gigabytes.

Faced with the problem of reading the 840 Evo, overclock.net forum user Techie007 created a very useful SSD Read Speed ​​Tester utility that can graph the read performance of individual files depending on their age. Hansson also checked his 840, and concluded that the reading problem was confirmed.

The visualization of the result is limited to 99 weeks, and there was older data on the disk. Hansson built a graph in Excel using raw data, days are plotted on the abscissa. When analyzing the results of the data, it becomes clear that the older the file, the worse it is read.

For comparison, this is the result of the Samsung 840 Pro, which uses MLC NAND memory cells that store two bits and require calibration of only four voltage levels. There is no drop in reading speed on it.

Another interesting observation was the dependence of performance on temperature. The benchmark results «floated», and Hansson found that this was due to the temperature of the drive. The warmer 840, the better old data is read. But this may not be true for all types of solids — they can be calibrated to a different temperature. It is also impossible to increase the temperature above the threshold: in case of overheating, the controller will limit the data transfer rate. These phenomena once again emphasize how difficult it is to correct the reading algorithm.

At 15°C, the speed is noticeably slower than at 40°C.