Samsung SSD 840 EVO mSATA (120GB, 250GB, 500GB & 1TB) Review
by Kristian Vättö on January 9, 2014 1:35 PM ESTThe NAND: Going Vertical, Not 3D (Yet)
Since we are dealing with a fixed number of NAND packages (unless you want to do Mushkin's and build a dual-PCB design), there are two ways to increase the capacity. One is to increase the capacity per die, which is what has been done before. This is a logical way as the lithographies get smaller (3Xnm was 32Gb, 2Xnm 64Gb and now 1X/2Ynm 128Gb) and you can double the capacity per die while keeping the die are roughly the same as with the previous process node. However, it's not very efficient to increase the capacity per die unless there is a die shrink because otherwise the end result is a large die, which is generally bad for yields and that in turn is bad for financials. Since we are still moving to 128Gb die (Samsung and IMFT have moved already, Toshiba/SanDisk and SK Hynix are still using 64Gb), moving to 256Gb die this quickly was out of question. I do not expect 256Gb die to happen until 2015/2016 and it may well be that we will not even see manufacturers going past 128Gb at that point. We'll see a big push for 3D NAND during the next few years and I am not sure if planar NAND will get to a point where 256Gb die becomes beneficial.
| Samsung SSD 840 EVO mSATA NAND Configurations | ||||
| Capacity | 120GB | 250GB | 500GB | 1TB |
| Raw NAND Capacity | 128GiB | 256GiB | 512GiB | 1024GiB |
| # of NAND Packages | 2 | 2 | 4 | 4 |
| # of Dies per Package | 4 | 8 | 8 | 16 |
| Capacity per Die | 16GiB | 16GiB | 16GiB | 16GiB |
| Over-Provisioning | 12.7% | 9.1% | 9.1% | 9.1% |
If you cannot increase the capacity per die, the only way left is to increase the die count. So far the limit has been eight dies and with traditional packaging methods there is already some performance loss after exceeding four dies per package. That is due to the limits of the interconnects that connect the dies to the PCB and as you add more dies the signal integrity degrades and latency goes up exponentially.
Source: Micron
In order to achieve the 1TB capacity with only four NAND packages, Samsung had to squeeze sixteen NAND dies into one package. To my surprise, when I started researching a bit about Samsung's 16-die NAND, I found out that it's actually nothing new. Their always-so-up-to-date NAND part number decoder from August 2009 mentions a 16-die MLC configuration and I managed to find TechInsights' report of a 512GB SSD used in 2012 Retina MacBook Pro with x-ray shots of a 16-die NAND package. That is a SSD 830 based drive, so I circled back to check the NAND used in the 512GB SSD 830 and it indeed has sixteen 32Gb dies per package too.
Courtesy of TechInsights
I also made a graph based on the x-ray shot since it's not exactly clear unless you know what you're looking for.
Unfortunately I couldn't find any good x-ray shots of other manufacturers' NAND to see if Samsung's packaging method is different, which would explain their ability to ship a 16-die package with no significant performance loss. However, what I was able to find suggested that others use similar packaging (i.e. an inclinated tower of dies with interconnects falling from both sides). Samsung is also very tight-lipped about their NAND and the technologies involved, so I've not been able to get any details out of them. Anand is meeting with their SSD folks at CES and there is hope that he will be able to convince them to give us even a brief overview.
I am thinking this is not strictly hardware related but software too. In the end, the problem is signal integrity and latency, both which can be overcome with high quality engineering. The two are actually related: Poor signal integrity means more errors, which in turn increases latency because it's up to the ECC engine to fix the error. The more errors there are, the longer it obviously takes. With an effective combination of DSP and ECC (and a bunch of other acronyms), it's possible to stack more dies without sacrificing performance. Samsung's control over the silicon is a huge help here -- ECC needs to be built into the hardware to be efficient and since it's up to Samsung to decide how much resources and die area they want to devote to ECC, they can make it happen.
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Brenderick - Saturday, February 15, 2014 - link
mSata was what the commenter wanted.MoFoQ - Friday, January 10, 2014 - link
same hardware?The mSATA version has 4 NAND packages.
The 2.5" version has 8.
Sure, the number of dies total might be the same.
It's like comparing two houses of the same square-footage....except one of them is a two-story house and the other, a single-story one.
With that said, it is an interesting development for mSATA SSDs.
I can't wait until other manufacturers come to market to help drive the price down.
emvonline - Friday, January 10, 2014 - link
16 die packages are possible at all NAND suppliers and it is relatively straight forward to implement. the issue is usually that there is minimal demand for anything requiring it. What percentage of the market is 1TB? I think we are talking less than 3% above 512G for consumers. let me know if I am wrong.TLC is great for Samsung product margins. so far it hasn't led to a cost decrease for consumers.
Samsung's execution is the amazing part. they have good (or great) products in every market at every density. And they have the most aggressive marketing campaign. No one else has been able to achieve this.
Marrixster - Saturday, January 11, 2014 - link
Thanks very much indeed for this review. I already have 2 Samsung PM851 512GB (MZMTE512HMHP-00000). And, just prior to reading this review ordered the 1TB model (MZ-MTE1T0BW).The price is AUD822.99 (ramcity.com.au), very expensive. However, the convenience of this form factor justifies cost from my point of view.
Now, it's simply a matter of deciding which lappy it gets installed in.
Unit Igor - Saturday, January 11, 2014 - link
Tell me Kristian please would EVO 120GB msata have any advantage over EVO 250gb msata in longer battery life when you compare power consumption vs. disk busy times and mb/s.I use my ultrabook only for mails ,sometimes watching movies and surfing.I dont need more then 120GB SSD but i am willing to buy 250Gb if it would give me more battery life.What i wanted to see in your benchmark is MobileMark 2012 because msata is for laptops and that is where battery life play big role.philipma1957 - Sunday, January 12, 2014 - link
the new gigabyte brix with the i7 4770r cpu 16th ram and a 1tb mSata would be really nice gear.nogoms - Monday, January 13, 2014 - link
You start off with the claim that "Samsung is in a unique position in the SSD market. It’s the only company in the consumer SSD business with a fully vertically integrated business model and zero reliance on other companies."This is, however, not actually true. SK Hynix is in a similar position, as they've had their own controllers, NAND, and DRAM since their purchase of LAMD a year and a half ago. Admittedly, they hadn't actually released a completely in-house SSD using a LAMD controller until late last year with the release of the SH 920 series. In fact, the Surface Pro 2 uses an SK Hynix mSATA SSD (with a LAMD controller), as noted in Anand's review and iFixIt's teardown. SK Hynix also doesn't appear to be making the SH920 series available in retail outside of Asia, though Super Talent's Supernova3 series is available in retail in North America (from the likes of SuperBiiz and various third-party sellers on Amazon and Newegg) and appears to be rebranded 2.5" SK Hynix SH920 series drives.
Kristian Vättö - Monday, January 13, 2014 - link
I did mention SK Hynix and LAMD later in the article:"Sure, Samsung isn't the only NAND manufacturer but it is the only one with a consumer orientated controller IP (although SK Hynix owns LAMD now but that deal has yet to materialize in a product)"
The thing is, while Hynix does have a LAMD based SSD, it's the same controller that other's are using. It's possible that Hynix has contributed to the firmware but it's not a fully in-house designed platform (the controller was designed way before the acquisition took place).
nogoms - Monday, January 13, 2014 - link
That statement is also false, as SK Hynix's LAMD controller *has* materialized in products, as I pointed out in my previous post--they're available in complete systems like the Surface Pro 2 worldwide as well as standalone at retail (in East Asia). Also, it's disingenuous to say it's not fully in-house when the controller and firmware were designed and written by teams currently in the employ of SK Hynix, and even if one were to accept your contention that such an arrangement is not "fully in-house designed," the opening statement of the article does not all of a sudden become true, as Samsung is still not the only manufacturer with "a fully integrated business model" or "zero reliance on other companies."Hrel - Monday, January 13, 2014 - link
any idea when we'll be able to get 512GB drives for under $200?