What Micron's Upcoming 3D NAND Means for SSD Capacity, Performance, and Cost

Subject: Storage | February 14, 2016 - 02:51 PM |
Tagged: vnand, ssd, Samsung, nand, micron, Intel, imft, 768Gb, 512GB, 3d nand, 384Gb, 32 Layer, 256GB

You may have seen a wave of Micron 3D NAND news posts these past few days, and while many are repeating the 11-month old news with talks of 10TB/3.5TB on a 2.5"/M.2 form factor SSDs, I'm here to dive into the bigger implications of what the upcoming (and future) generation of Intel / Micron flash will mean for SSD performance and pricing.

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Remember that with the way these capacity increases are going, the only way to get a high performance and high capacity SSD on-the-cheap in the future will be to actually get those higher capacity models. With such a large per-die capacity, smaller SSDs (like 128GB / 256GB) will suffer significantly slower write speeds. Taking this upcoming Micron flash as an example, a 128GB SSD will contain only four flash memory dies, and as I wrote about back in 2014, such an SSD would likely see HDD-level sequential write speeds of 160MB/sec. Other SSD manufacturers already recognize this issue and are taking steps to correct it. At Storage Visions 2016, Samsung briefed me on the upcoming SSD 750 Series that will use planar 16nm NAND to produce 120GB and 250GB capacities. The smaller die capacities of these models will enable respectable write performance and will also enable them to discontinue their 120GB 850 EVO as they transition that line to higher capacity 48-layer VNAND. Getting back to this Micron announcement, we have some new info that bears analysis, and that pertains to the now announced page and block size:

  • 256Gb MLC: 16KB Page / 16MB Block / 1024 Pages per Block

  • 384Gb TLC: 16KB Page / 24MB Block / 1536 Pages per Block

To understand what these numbers mean, using the MLC line above, imagine a 16MB CD-RW (Block) that can write 1024 individual 16KB 'sessions' (Page). Each 16KB can be added individually over time, and just like how files on a CD-RW could be modified by writing a new copy in the remaining space, flash can do so by writing a new Page and ignoring the out of date copy. Where the rub comes in is when that CD-RW (Block) is completely full. The process at this point is very similar actually, in that the Block must be completely emptied before the erase command (which wipes the entire Block) is issued. The data has to go somewhere, which typically means writing to empty blocks elsewhere on the SSD (and in worst case scenarios, those too may need clearing before that is possible), and this moving and erasing takes time for the die to accomplish. Just like how wiping a CD-RW took a much longer than writing a single file to it, erasing a Block takes typically 3-4x as much time as it does to program a page.

With that explained, of significance here are the growing page and block sizes in this higher capacity flash. Modern OS file systems have a minimum bulk access size of 4KB, and Windows versions since Vista align their partitions by rounding up to the next 2MB increment from the start of the disk. These changes are what enabled HDDs to transition to Advanced Format, which made data storage more efficient by bringing the increment up from the 512 Byte sector up to 4KB. While most storage devices still use 512B addressing, it is assumed that 4KB should be the minimum random access seen most of the time. Wrapping this all together, the Page size (minimum read or write) is 16KB for this new flash, and that is 4x the accepted 4KB minimum OS transfer size. This means that power users heavy on their page file, or running VMs, or any other random-write-heavy operations being performed over time will have a more amplified effect of wear of this flash. That additional shuffling of data that must take place for each 4KB write translates to lower host random write speeds when compared to lower capacity flash that has smaller Page sizes closer to that 4KB figure.

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A rendition of 3D IMFT Floating Gate flash, with inset pulling back some of the tunnel oxide layer to show the location of the floating gate. Pic courtesy Schiltron.

Fortunately for Micron, their choice to carry Floating Gate technology into their 3D flash has netted them some impressive endurance benefits over competing Charge Trap Flash. One such benefit is a claimed 30,000 P/E (Program / Erase) cycle endurance rating. Planar NAND had dropped to the 3,000 range at its lowest shrinks, mainly because there was such a small channel which could only store so few electrons, amplifying the (negative) effects of electron leakage. Even back in the 50nm days, MLC ran at ~10,000 cycle endurance, so 30,000 is no small feat here. The key is that by using that same Floating Gate tech so good at controlling leakage for planar NAND on a new 3D channel that can store way more electrons enables excellent endurance that may actually exceed Samsung's Charge Trap Flash equipped 3D VNAND. This should effectively negate the endurance hit on the larger Page sizes discussed above, but the potential small random write performance hit still stands, with a possible remedy being to crank up the Over-Provisioning of SSDs (AKA throwing flash at the problem). Higher OP means less active pages per block and a reduction in the data shuffling forced by smaller writes.

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A 25nm flash memory die. Note the support logic (CMOS) along the upper left edge.

One final thing helping out Micron here is that their Floating Gate design also enables a shift of 75% of the CMOS circuitry to a layer *underneath* the flash storage array. This logic is typically part of what you see 'off to the side' of a flash memory die. Layering CMOS logic in such a way is likely thanks to Intel's partnership and CPU development knowledge. Moving this support circuitry to the bottom layer of the die makes for less area per die dedicated to non-storage, more dies per wafer, and ultimately lower cost per chip/GB.

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Samsung's Charge Trap Flash, shown in both planar and 3D VNAND forms.

One final thing before we go. If we know anything about how the Intel / Micron duo function, it is that once they get that freight train rolling, it leads to relatively rapid advances. In this case, the changeover to 3D has taken them a while to perfect, but once production gains steam, we can expect to see some *big* advances. Since Samsung launched their 3D VNAND their gains have been mostly iterative in nature (24, 32, and most recently 48). I'm not yet at liberty to say how the second generation of IMFT 3D NAND will achieve it, but I can say that it appears the next iteration after this 32-layer 256Gb (MLC) /384Gb (TLC) per die will *double* to 512Gb/768Gb (you are free to do the math on what that means for layer count). Remember back in the day where Intel launched new SSDs at a fraction of the cost/GB of the previous generation? That might just be happening again within the next year or two.

Samsung Launches 950 PRO - 300,000 IOPS and 2.5 GB/sec from a M.2 V-NAND SSD!

Subject: Storage | September 22, 2015 - 02:39 AM |
Tagged: vnand, V-NAND, ssd, Samsung, pcie, NVMe, M.2 2280, M.2, 950 PRO, 512GB, 256GB

I’ve been waiting a long time for Samsung to put their V-NAND flash memory into a PCIe connected SSD, and such a product has just been officially announced at the Samsung SSD Global Summit.

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Samsung’s new product launching will be called the 950 PRO. This will be an M.2 2280 form factor product running at PCIe 3.0 x4. Equipped with Samsung’s 32-layer V-NAND and using the NVMe protocol enabled by a new UBX controller, the 950 PRO will be capable of up to an impressive 300,000 random read IOPS. Random writes come in at 110,000 IOPS and sequential throughputs are expected to be 2.5 GB/sec reads and 1.5 GB/sec for writes. Available capacities will be 256GB and 512GB.

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Pricing:

The 950 PRO will be shipping with a 5-year warranty rated at 200 terabytes written for the 256GB model and 400 TBW for the 512GB. That works out to just over 100GB per day for both capacities.

These hit retail in October and we currently have samples in hand for testing.

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(for those curious, both capacities only have components on the front side of the PCB)

Full press blast after the break.

Source: Samsung
Subject: Storage
Manufacturer: Samsung

Introduction

Given that we are anticipating a launch of the Samsung 850 EVO very shortly, it is a good time to back fill on the complete performance picture of the 850 Pro series. We have done several full capacity roundups of various SSD models over the past months, and the common theme with all of them is that as the die count is reduced in lower capacity models, so is the parallelism that can be achieved. This effect varies based on what type of flash memory die is used, but the end result is mostly an apparent reduction in write performance. Fueling this issue is the increase in flash memory die capacity over time.

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There are two different ways to counteract the effects of write speed reductions caused by larger capacity / fewer dies:

  • Reduce die capacity.
  • Increase write performance per die.

Recently there has been a trend towards *lower* capacity dies. Micron makes their 16nm flash in both 128Gbit and 64Gbit. Shifting back towards the 64Gbit dies in lower capacity SSD models helps them keep the die count up, increasing overall parallelism, and therefore keeping write speeds and random IO performance relatively high.

Read on for the results of our full capacity roundup!

Subject: Storage
Manufacturer: ADATA

Introduction, Specifications and Packaging

Introduction:

It seems a lot of folks have been incorporating Silicon Motion's SM2246EN controller into their product lines. We first reviewed the Angelbird SSD wrk, but only in a 512GB capacity. We then reviewed a pair of Corsair Force LX's (256GB and 512GB). ADATA has joined the club with their new Premier SP610 product line, and today we are going to take a look at all available capacities of this new model:

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It's fortunate that ADATA was able to sample us a full capacity spread, as this will let us evaluate all shipping SSD capacites that exist for the Silicon Motion SM2246EN controller.

Continue reading as we evaluate the ADATA Premier SP610!

SanDisk Launches 512GB SDXC Card for $799.99

Subject: General Tech, Storage | September 12, 2014 - 04:08 PM |
Tagged: sandisk, sdxc, sdhc, sd card, 512GB

Assuming your camera, card reader, or other device fully conforms to the SDXC standard, Sandisk has developed a half-terabyte (512GB) memory card. Beyond being gigantic, it can be read at up to 95 MB/s and written at up to 90 MB/s, which should be enough to stream 4K video. Sandisk claims that it is temperature proof, shock proof, water proof, and x-ray proof. It also comes with a lifetime warranty and "RescuePRO Deluxe" recovery software but, honestly, I expect people would just use PhotoRec or something.

It should be noted that the SDXC standard covers memory cards up to 2TB so it will probably not be too long before we see another standard get ratified. What is next? SDUC? SDYC? SDALLTHEC? Blah! This is why IEEE assigns names sequentially.

The SanDisk Extreme PRO UHS-I SDHC/SDXC 512GB memory card should be available now, although I cannot yet find them online, for $799.99 MSRP.

Source: SanDisk
Subject: Storage
Manufacturer: Corsair

Introduction, Specifications and Packaging

Introduction:

We first looked at the Silicon Motion 2246EN controller in our Angelbird SSD wrk review. In that review, we noted the highest sequential performance seen in any SATA SSD reviewed to date. Eager to expand our testing to include additional vendors and capacities, our next review touching on this controller is the Corsair Force LX series of SSDs. The Force LX Series is available in 128GB, 256GB, and 512GB capacities, and today we will look at the 256GB and 512GB iterations of this line:

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Continue reading as we evaluate the Corsair Force LX series:

Angelbird mixes style and performance with the wrk

Subject: Storage | August 18, 2014 - 03:15 PM |
Tagged: 512GB, angelbird, silicon motion, SMI, ssd, wrk

The simple look and extra care that went into manufacturing the Angelbird wrk SSDs show that they are serious about breaking into the market.  They have launched at a price slightly higher than average for the market but also bring the best sequential reads that Al has seen yet on a SATA drive.  Legit Reviews pried the drive open to reveal the Silicon Motion SM2246EN SATA III 6Gbps SSD controller previously seen on Corsair, PNY, ADATA and Transcend SSDs, along with MLC flash and 256MB of DDR3 cache.  In Legit Reviews testing of the drive they concluded that you should pick up the 256GB or 512GB model for the extra performance that it brings, you will not be disappointed.

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"Angelbird might night be a household name, but the Austrian company has been around in the SSD market for a number of years and has gotten a reputation for having high quality products. When we found out that Angelbird was coming out with a new SSD product like called the SSD wrk we couldn’t wait to get our hands on one of these drives and see what Angelbird has to offer consumers. Read on to find out!"

Here are some more Storage reviews from around the web:

Storage

Subject: Storage
Manufacturer: Angelbird

Introduction, Specifications and Packaging

Introduction:

You might have never heard of Angelbird - until now, that is. Angelbird Technologies GmbH is an SSD maker based out of Vorarlberg, Austria. Their product lines have historically focused around high end and Mac-based products, with a recent arch into portable SSDs (like their SSD2go line). Angelbird is known for their high build quality, and their products are assembled using a technique I can appreciate - vapor phase soldering - (seen here) a technique that puts the least possible thermal stress on the components, as well as ensuring all solder joints are oxygen free. While the vast majority of the their prior products have been build around SandForce controllers, today they have launched a new line, the SSD wrk:

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The Angelbird SSD wrk is built around a new (to them) controller, the SM2246EN from Silicon Motion:

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Silicon Motion prides themselves on making SSD controllers that deliver good performance at very low power consumption. For those wanting more detail on this particular controller technology, we have a detailed analysis from last August, available at this page.

Continue reading as we evaluate the new Angelbird SSD wrk!

What is in a brand? The tale of two low cost SSDs

Subject: Storage | July 28, 2014 - 03:52 PM |
Tagged: adata, SP610, corsair, Force LX, 512GB

Two drives are competing for the budget segments money on Legit Reviews, the $250 Corsair Force LX 512GB and the $240 ADATA SP610 512GB SSD.  512GB should be enough for most budget users to store their needed software on and save them the cost of an HDD but which will offer the most value for the money?  Both drives have Silicon Motion's SM2246EN controller and 20nm Micron MLC NAND, the same 3 year warranty and the same physical measurements.  Does one stand out over the other?  Read the full review to see.

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"Solid-State Drive (SSD) have been steadily growing in capacity and thanks to improvements to the manufacturing processes the price of NAND and SSD controllers has been falling at an impressive rate. This means that fairly large SSDs are now fairly affordable and something the for the average consumer can justify purchasing."

Here are some more Storage reviews from around the web:

Storage

Subject: Storage
Manufacturer:

Introduction, Specifications and Packaging

Introduction:

A few months back, we took a look at the ADATA Premier Pro SP920 series of SSDs. Those came equipped with the Marvell 88SS9189 controller. Marvell SSD controllers have always done a good job, and they were among the first to support SATA 6Gbit speeds. Crucial was one of the first to adopt the Marvell controller into their SATA SSD products, so it seems fitting that we revisit the 88SS9189 controller in the form of Micron's Crucial M550 Series of SSDs:

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Being one of the big manufacturers of SSDs, Micron has some cool production videos. Here's one of their videos covering the production of flash all the way through to the assembly of an SSD. We actually toured one of these plants a few years back. Good stuff:

Continue reading as we evaluate all available capacities of the Crucial M550!!