Samsung SSD 840 EVO Review: 120GB, 250GB, 500GB, 750GB & 1TB Models Testedby Anand Lal Shimpi on July 25, 2013 1:53 PM EST
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- Samsung SSD 840
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.
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|
|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||?||?||?|
|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.
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).
|Samsung SSD 840 EVO DRAM|
|DRAM Size||256MB LPDDR2-1066||512MB LPDDR2-1066||512MB LPDDR2-1066||1GB LPDDR2-1066||1GB LPDDR2-1066|
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|
|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||
|Max Sequential Write||
|Max 4KB Random Read||
|Max 4KB Random Write||
|Encryption||AES-256 FDE, PSID printed on SSD label|
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.
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|
|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.
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verjic - Thursday, February 13, 2014 - linkI'm talking about 120 Gb version
verjic - Thursday, February 13, 2014 - linkAlso what is Write/Read IOMeter Bootup and Write/Read IOMeter IOMix - what means their speed? Thank You
AhDah - Thursday, May 15, 2014 - linkThe TRIM validation graph shows a tremendous performance drop after a few gigs of writes, even after TRIM pass, the write speed is only 150MBps.
Does this mean once the drive is 75%-85% filled up, the write speed will always be slow?
I'm tempted to get Crucial M550 because of this down fall.
njwhite2 - Wednesday, October 15, 2014 - linkKudos to Anand Lal Shimpi! This is one of the finest reviews I have ever read! No jargon. No unexplained acronyms. Quantitative testing of compared items instead of reviewer bias. Explanation of why the measured criteria are imortant to the end user! Just fabulous! I read dozens of reviews each week, so I'm surprised I had not stumbled upon Anandtech before. I'm (for sure) going to check out their smartphone reviews. Most of those on other sites are written by Apple fans or Android fans and really don't tell the potential purchaser what they need to know to make the best choice for them.
IT_Architect - Thursday, October 22, 2015 - linkI would be interested in how reliable they are. The reason I ask is one time, when the time the Intel SLC technology was just under two years old, and there was no MLC or TLC, I needed speed to load a database from scratch 6 times an hour during incredible traffic times. I was getting requests by users at the rate of 66 times a second per server, which each required many reads of the database per request. I couldn't swap databases without breaking sessions, and mirror and unmirror did not work well. I would have to pay a ton to duplicate a redundant array in SSDs. Then I asked the data center how many of these drives they had out there. They (SoftLayer) queried and came back with 700+. Then I asked them how many they've had go bad. They queried their records and it was none, not so much as a DOA. I reasoned from that I would be just as likely to have a chassis or disk controller go bad. None of them have any moving parts, and the drives are low power. Those were enterprise drives of course because that's all there was at that time.
In 2011 I bought a Dell M6600. Dell was shipping them with the Micron SSD. I was concerned about the lifespan and I do a lot of reading and writing with it and work constantly with virtual machines while prototyping, and VM files are huge. It calculated out to 4 years. While researching, I came across that situation where Dell had "cold feet" about OEMing them due to lifespan. Micron/Intel demonstrated to them 10x the rated lifespan, which convinced Dell. There was plenty of other trouble with consumer-level SSDs at the time, which gave the technology a bad name. The Micron/Intel was one of the very few solid citizens at the time. I went with it, although I didn't buy my M6600 with it because Dell had such a premium on them. I had two problems with the drive, which by the way is still in service today. The first was the drive just stopped doing anything one day. I called Micron and it turned out to be a bug in the firmware. If I had two drives arrayed, it would have stopped both at the same time. I upgraded the firmware and never had that problem again. The next time I was troubleshooting the laptop and putting the battery in and out and the computer would no longer boot. I again called Micron. It was by design. They said disconnect the power, pull the battery, and wait one hour. I did, and it has worked perfectly since. If I had an array, it would have stopped both at the same time.
Today, the market is much more mature and the technology no longer has a bad name. A redundant array is no substitute for a backup anyway. A redundant array brings business continuity and speed. Are we just as likely or more so to have a motherboard go out? We don't have redundant motherboards unless without having another entire computer. Unlike a power supplies and CPUs, SSDs are low-current devices. I'm considering the possibility that we may be at the point, even for consumer-level drives, where redundant arrays for SSDs are just plain silly.
Gothmoth - Sunday, January 8, 2017 - linkin real life my RAPID test showed no benefits AT ALL!!
all it does is making low level benchmarks look better.
you should test with real applications. RAPID is a useless feature.
jeyjey - Friday, June 7, 2019 - linkI have one of this drive. I need to find a little part that is fired, I need to replace it to try to enter the data inside. Please help.