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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eamon - Thursday, August 1, 2013 - linkUnless you want to run some kind of continual I/O server, I suspect performance will be fast enough not to matter; I'd only look at pricing if I were you...
Busverpasser - Thursday, August 8, 2013 - linkHi there, great review, thanks a lot. Actually I do have a question... The article says "The performance story is really good (particularly with the larger capacities), performance consistency out of the box is ok (and gets better if you can leave more free space on the drive)..."
Does leaving more free space mean that this space is supposed to be unpartitioned or just not filled with data? When I bought my Intel Postville SSD some time ago, I left some space unpartitioned but never really knew whether that was the right thing to do :D. Can someone give me a hint here?
xchaotic - Wednesday, August 14, 2013 - link@Busverpasser just leave more space free, it doesn't have to be unpartitioned.
Worst case if you need that extra space for a while, you'll get lower performance, but more storage whenever you need it.
speculatrix - Saturday, August 17, 2013 - linkthe table titled "Samsung SSD 840 EVO TurboWrite Buffer Size vs. Capacity" should be titled "Capacity vs Usage vs Endurance"
rdugar - Friday, August 23, 2013 - linkAm in the market for an SSD finally to replace an HDD on a Windows 7 laptop. Was almost set on the 128GB Samsung 840 Pro, but saw the comment on poor performance at almost full capacities.
Price, reliability and endurance being the most important to me, which one should I go for?
128Gb Samsung 840 Pro? approx $119 after coupons, etc.
120 GB Samsung 840 EVO? probably $99 or so
256 GB Samsung 840 EVO? probably $165 or so
Other brand and model?
If I have to spend $120 odd, may as well spend another $50 and get double the capacity....
tfop - Saturday, August 24, 2013 - linkI have a question regarding to the NAND Comparison table.
How do this Page and Block sizes affect the right Clustersize and Alignment of the Partition?
If i am getting this right, the SSD 840 EVO would need a 8 KiB Clustersize and a 2 MiB Alignment.
Gnomer87 - Wednesday, August 28, 2013 - linkI have a couple of questions:
First, how much data is typically written to the average consumer HDD on a daily basis these days? I am thinking it's nowhere close to 50GiB. I guess what I am really interested in knowing, is how much data the operating system(windows 7) writes to the drive for various maintenance uses(if there are any beside defragmenting). In my mind, simply booting up the computer shouldn't mean any writes to the drive at all. Ergo, given my typical use, a 120GB SSD of that caliber, should last a lifetime. Am I right in thinking this? I mean, reading doesn't affect the durability right?
Secondly: I've been considering getting an SSD for use as a OS drive for a long time, reason of course was to speed up boot time. However, I've long wondered WHY windows boots so slowly from HDDs in the first place. After all, the amount of data loaded during boot up isn't large. In my case the processes post-boot take up around 200 MBs, Assuming the actual amount of data loaded from the drive is about the same, it really shouldn't take that long. My HDD is capable of reading up to 120 MBs in optimal situations, so it's obvious the boot up process isn't optimal by a long shot.
But why this slow? It can take over a minute before she(my computer) is done loading and starting all processes. Last semester I took course in Operating system at the local university. I must confess I was a horrible student, I didn't show up much. But I do remember a few key elements, namely the scheduler and how this scheduler continually does context switches, letting each process use the CPU, and thus creating parallelism. Now what was really interesting was resource management. It's the scheduler that decides which process is currently running on the cpu, and the scheduler process is run in between each context switch, effectively letting each user process run and have access to resources, such as the hard drive. Now, what happens if all the processes want data from the drive at the same time? Would each process continually interrupt the other processes loading of data, and thus causing the HDD to seek constantly?
Could that explain why booting takes such idiotic amounts of time? An extremely inefficient resource management that basically ignores the inherent seek-time related weaknesses of an HDD? SSDs, as we know, barely have seek-time, and thus the performance loss from context switching should be negligible.
I know my cousins SSD powered computer boots near instantly, once it's done with the usual BIOS stuff, the OS is booted and ready for use in mere seconds. And yes, we are talking a completely cold boot here, no sleep or anything like that.
abhilashjain30 - Friday, September 20, 2013 - linkI purchased Samsung 120GB EVO 3 days back from OnlySSD ( http://goo.gl/HqgjId )and Drive performance is too good compare to 120GB 840 Basic Series.
abhilashjain30 - Friday, September 20, 2013 - linkAvailable at OnlySSD dot com
abhilashjain30 - Wednesday, October 2, 2013 - linkSamsung Evo Series now available online in India. You can check on OnlySSD dot com or PrimeABGB dot com