Fadu's FC5161 SSD Controller Breaks Cover in Western Digital's PCIe Gen5 Enterprise Drives
When Western Digital introduced its Ultrastar DC SN861 SSDs earlier this year, the company did not disclose which controller it used for these drives, which made many observers presume that WD was using an in-house controller. But a recent teardown of the drive shows that is not the case; instead, the company is using a controller from Fadu, a South Korean company founded in 2015 that specializes on enterprise-grade turnkey SSD solutions.
The Western Digital Ultrastar DC SN861 SSD is aimed at performance-hungry hyperscale datacenters and enterprise customers which are adopting PCIe Gen5 storage devices these days. And, as uncovered in photos from a recent Storage Review article, the drive is based on Fadu's FC5161 NVMe 2.0-compliant controller. The FC5161 utilizes 16 NAND channels supporting an ONFi 5.0 2400 MT/s interface, and features a combination of enterprise-grade capabilities (OCP Cloud Spec 2.0, SR-IOV, up to 512 name spaces for ZNS support, flexible data placement, NVMe-MI 1.2, advanced security, telemetry, power loss protection) not available on other off-the-shelf controllers – or on any previous Western Digital controllers.
The Ultrastar DC SN861 SSD offers sequential read speeds up to 13.7 GB/s as well as sequential write speeds up to 7.5 GB/s. As for random performance, it boasts with an up to 3.3 million random 4K read IOPS and up to 0.8 million random 4K write IOPS. The drives are available in capacities between 1.6 TB and 7.68 TB with one or three drive writes per day (DWPD) over five years rating as well as in U.2 and E1.S form-factors.
While the two form factors of the SN861 share a similar technical design, Western Digital has tailored each version for distinct workloads: the E1.S supports FDP and performance enhancements specifically for cloud environments. By contrast, the U.2 model is geared towards high-performance enterprise tasks and emerging applications like AI.
Without any doubts, Western Digital's Ultrastar DC SN861 is a feature-rich high-performance enterprise-grade SSD. It has another distinctive feature: a 5W idle power consumption, which is rather low by the standards of enterprise-grade drives (e.g., it is 1W lower compared to the SN840). While the difference with predecessors may be just 1W, hyperscalers deploy thousands of drives and for their TCO every watt counts.
Western Digital's Ultrastar DC SN861 SSDs are now available for purchase to select customers (such as Meta) and to interested parties. Prices are unknown, but they will depend on such factors as volumes.
Sources: Fadu, Storage Review
Storage
Posted by The Techinical Support
Kioxia Details BiCS 8 NAND at FMS 2024: 218 Layers With Superior Scaling 
Kioxia's booth at FMS 2024 was a busy one with multiple technology demonstrations keeping visitors occupied. A walk-through of the BiCS 8 manufacturing process was the first to grab my attention. Kioxia and Western Digital announced the sampling of BiCS 8 in March 2023. We had touched briefly upon its CMOS Bonded Array (CBA) scheme in our coverage of Kioxial's 2Tb QLC NAND device and coverage of Western Digital's 128 TB QLC enterprise SSD proof-of-concept demonstration. At Kioxia's booth, we got more insights.
Traditionally, fabrication of flash chips involved placement of the associate logic circuitry (CMOS process) around the periphery of the flash array. The process then moved on to putting the CMOS under the cell array, but the wafer development process was serialized with the CMOS logic getting fabricated first followed by the cell array on top. However, this has some challenges because the cell array requires a high-temperature processing step to ensure higher reliability that can be detrimental to the health of the CMOS logic. Thanks to recent advancements in wafer bonding techniques, the new CBA process allows the CMOS wafer and cell array wafer to be processed independently in parallel and then pieced together, as shown in the models above.
The BiCS 8 3D NAND incorporates 218 layers, compared to 112 layers in BiCS 5 and 162 layers in BiCS 6. The company decided to skip over BiCS 7 (or, rather, it was probably a short-lived generation meant as an internal test vehicle). The generation retains the four-plane charge trap structure of BiCS 6. In its TLC avatar, it is available as a 1 Tbit device. The QLC version is available in two capacities - 1 Tbit and 2 Tbit.
Kioxia also noted that while the number of layers (218) doesn't compare favorably with the latest layer counts from the competition, its lateral scaling / cell shrinkage has enabled it to be competitive in terms of bit density as well as operating speeds (3200 MT/s). For reference, the latest shipping NAND from Micron - the G9 - has 276 layers with a bit density in TLC mode of 21 Gbit/mm2, and operates at up to 3600 MT/s. However, its 232L NAND operates only up to 2400 MT/s and has a bit density of 14.6 Gbit/mm2.
It must be noted that the CBA hybrid bonding process has advantages over the current processes used by other vendors - including Micron's CMOS under array (CuA) and SK hynix's 4D PUC (periphery-under-chip) developed in the late 2010s. It is expected that other NAND vendors will also move eventually to some variant of the hybrid bonding scheme used by Kioxia.
Storage
Micron Ships Denser & Faster 276 Layer TLC NAND, Arriving First In Micron 2650 Client SSDs 
Micron on Tuesday announced that the company has begun shipping its 9th Generation (G9) 276 layer TLC NAND. The next generation of NAND from the prolific memory maker, Micron's latest NAND is designed to further push the envelope on TLC NAND performance, offering significant density and performance improvements over its existing NAND technology.
Micron's G9 TLC NAND memory features 276 active layers, which is up from 232-layers in case of Micron's previous generation TLC NAND. At this point the company is being light on technical details in their official material. However in a brief interview with Blocks & Files, the company confirmed that their 276L NAND still uses a six plane architecture, which was first introduced with the 232L generation. At this point we're assuming Micron is also string-stacking two decks of NAND together, as they have been for the past couple of generations, which means we're looking at 138 layer decks.
| Micron TLC NAND Flash Memory | |||
| 276L | 232L (B58R) |
176L (B47R) |
|
| Layers | 276 | 232 | 176 |
| Decks | 2 (x138)? | 2 (x116) | 2 (x88) |
| Die Capacity | 1 Tbit | 1 Tbit | 512 Gbit |
| Die Size (mm2) | ~48.9mm2 | ~70.1mm2 | ~49.8mm2 |
| Density (Gbit/mm2) | ~21 | 14.6 | 10.3 |
| I/O Speed | 3.6 GT/s (ONFi 5.1) |
2.4 GT/s (ONFi 5.0) |
1.6 GT/s (ONFI 4.2) |
| Planes | 6 | 6 | 4 |
| CuA / PuC | Yes | Yes | Yes |
On the density front, Micron told Blocks & Files that they have improved their NAND density by 44% over their 232L generation. Which, given what we know about that generation, would put the density at around 21 Gbit/mm2. Or for a 1Tbit die of TLC NAND, that works out to a die size of roughly 48.9mm2, comparable to the die size of a 512Gbit TLC die from Micron's older 176L NAND.
Besides improving density, the other big push with Micron's newest generation of NAND was further improving its throughput. While the company's 232L NAND was built against the ONFi 5.0 specification, which topped out at transfer rates of 2400 MT/sec, their new 276L NAND can hit 3600 MT/sec, which is consistent with the ONFi 5.1 spec.
Meanwhile, the eagle-eyed will likely also pick up on Micron's ninth-generation/G9 branding, which is new to the company. Micron's has not previously used this kind of generational branding for their NAND, which up until now has simply been identified by its layer count (and before the 3D era, its feature size). Internally, this is believed to be Micron's 7th generation 3D NAND architecture. However, taking a page from the logic fab industry, Micron seems to be branding it as ninth-generation in order to keep generational parity with its competitors, who are preparing their own 8th/9th generation NAND (and thus cliam that they are the first NAND maker to ship 9th gen NAND).
And while this NAND will eventually end up in ... SSDs
CXL Gathers Momentum at FMS 2024 
The CXL consortium has had a regular presence at FMS (which rechristened itself from 'Flash Memory Summit' to the 'Future of Memory and Storage' this year). Back at FMS 2022, the company had announced v3.0 of the CXL specifications. This was followed by CXL 3.1's introduction at Supercomputing 2023. Having started off as a host to device interconnect standard, it had slowly subsumed other competing standards such as OpenCAPI and Gen-Z. As a result, the specifications started to encompass a wide variety of use-cases by building a protocol on top of the the ubiquitous PCIe expansion bus. The CXL consortium comprises of heavyweights such as AMD and Intel, as well as a large number of startup companies attempting to play in different segments on the device side. At FMS 2024, CXL had a prime position in the booth demos of many vendors.
The migration of server platforms from DDR4 to DDR5, along with the rise of workloads demanding large RAM capacity (but not particularly sensitive to either memory bandwidth or latency), has opened up memory expansion modules as one of the first set of widely available CXL devices. Over the last couple of years, we have had product announcements from Samsung and Micron in this area.
SK hynix CMM-DDR5 CXL Memory Module and HMSDK
At FMS 2024, SK hynix was showing off their DDR5-based CMM-DDR5 CXL memory module with a 128 GB capacity. The company was also detailing their associated Heterogeneous Memory Software Development Kit (HMSDK) - a set of libraries and tools at both the kernel and user levels aimed at increasing the ease of use of CXL memory. This is achieved in part by considering the memory pyramid / hierarchy and relocating the data between the server's main memory (DRAM) and the CXL device based on usage frequency.
The CMM-DDR5 CXL memory module comes in the SDFF form-factor (E3.S 2T) with a PCIe 3.0 x8 host interface. The internal memory is based on 1α technology DRAM, and the device promises DDR5-class bandwidth and latency within a single NUMA hop. As these memory modules are meant to be used in datacenters and enterprises, the firmware includes features for RAS (reliability, availability, and serviceability) along with secure boot and other management features.
SK hynix was also demonstrating Niagara 2.0 - a hardware solution (currently based on FPGAs) to enable memory pooling and sharing - i.e, connecting multiple CXL memories to allow different hosts (CPUs and GPUs) to optimally share their capacity. The previous version only allowed capacity sharing, but the latest version enables sharing of data also. SK hynix had presented these solutions at the CXL DevCon 2024 earlier this year, but some progress seems to have been made in finalizing the specifications of the CMM-DDR5 at FMS 2024.
Microchip and Micron Demonstrate CZ120 CXL Memory Expansion Module
Micron had unveiled the CZ120 CXL Memory Expansion Module last year based on the Microchip SMC 2000 series CXL memory controller. At FMS 2024, Micron and Microchip had a demonstration of the module on a Granite Rapids server.
Additional insights into the SMC 2000 controller were also provided.
The CXL memory controller also incorporates DRAM die failure handling, and Microchip also provides diagnostics and debug tools to analyze failed modules. The memory controller also supports ECC, which forms part of the enterprise... Storage
Kioxia Details BiCS 8 NAND at FMS 2024: 218 Layers With Superior Scaling
Kioxia's booth at FMS 2024 was a busy one with multiple technology demonstrations keeping visitors occupied. A walk-through of the BiCS 8 manufacturing process was the first to grab my attention. Kioxia and Western Digital announced the sampling of BiCS 8 in March 2023. We had touched briefly upon its CMOS Bonded Array (CBA) scheme in our coverage of Kioxial's 2Tb QLC NAND device and coverage of Western Digital's 128 TB QLC enterprise SSD proof-of-concept demonstration. At Kioxia's booth, we got more insights.
Traditionally, fabrication of flash chips involved placement of the associate logic circuitry (CMOS process) around the periphery of the flash array. The process then moved on to putting the CMOS under the cell array, but the wafer development process was serialized with the CMOS logic getting fabricated first followed by the cell array on top. However, this has some challenges because the cell array requires a high-temperature processing step to ensure higher reliability that can be detrimental to the health of the CMOS logic. Thanks to recent advancements in wafer bonding techniques, the new CBA process allows the CMOS wafer and cell array wafer to be processed independently in parallel and then pieced together, as shown in the models above.
The BiCS 8 3D NAND incorporates 218 layers, compared to 112 layers in BiCS 5 and 162 layers in BiCS 6. The company decided to skip over BiCS 7 (or, rather, it was probably a short-lived generation meant as an internal test vehicle). The generation retains the four-plane charge trap structure of BiCS 6. In its TLC avatar, it is available as a 1 Tbit device. The QLC version is available in two capacities - 1 Tbit and 2 Tbit.
Kioxia also noted that while the number of layers (218) doesn't compare favorably with the latest layer counts from the competition, its lateral scaling / cell shrinkage has enabled it to be competitive in terms of bit density as well as operating speeds (3200 MT/s). For reference, the latest shipping NAND from Micron - the G9 - has 276 layers with a bit density in TLC mode of 21 Gbit/mm2, and operates at up to 3600 MT/s. However, its 232L NAND operates only up to 2400 MT/s and has a bit density of 14.6 Gbit/mm2.
It must be noted that the CBA hybrid bonding process has advantages over the current processes used by other vendors - including Micron's CMOS under array (CuA) and SK hynix's 4D PUC (periphery-under-chip) developed in the late 2010s. It is expected that other NAND vendors will also move eventually to some variant of the hybrid bonding scheme used by Kioxia.
Storage
Micron Ships Denser & Faster 276 Layer TLC NAND, Arriving First In Micron 2650 Client SSDs
Micron on Tuesday announced that the company has begun shipping its 9th Generation (G9) 276 layer TLC NAND. The next generation of NAND from the prolific memory maker, Micron's latest NAND is designed to further push the envelope on TLC NAND performance, offering significant density and performance improvements over its existing NAND technology.
Micron's G9 TLC NAND memory features 276 active layers, which is up from 232-layers in case of Micron's previous generation TLC NAND. At this point the company is being light on technical details in their official material. However in a brief interview with Blocks & Files, the company confirmed that their 276L NAND still uses a six plane architecture, which was first introduced with the 232L generation. At this point we're assuming Micron is also string-stacking two decks of NAND together, as they have been for the past couple of generations, which means we're looking at 138 layer decks.
| Micron TLC NAND Flash Memory | |||
| 276L | 232L (B58R) |
176L (B47R) |
|
| Layers | 276 | 232 | 176 |
| Decks | 2 (x138)? | 2 (x116) | 2 (x88) |
| Die Capacity | 1 Tbit | 1 Tbit | 512 Gbit |
| Die Size (mm2) | ~48.9mm2 | ~70.1mm2 | ~49.8mm2 |
| Density (Gbit/mm2) | ~21 | 14.6 | 10.3 |
| I/O Speed | 3.6 GT/s (ONFi 5.1) |
2.4 GT/s (ONFi 5.0) |
1.6 GT/s (ONFI 4.2) |
| Planes | 6 | 6 | 4 |
| CuA / PuC | Yes | Yes | Yes |
On the density front, Micron told Blocks & Files that they have improved their NAND density by 44% over their 232L generation. Which, given what we know about that generation, would put the density at around 21 Gbit/mm2. Or for a 1Tbit die of TLC NAND, that works out to a die size of roughly 48.9mm2, comparable to the die size of a 512Gbit TLC die from Micron's older 176L NAND.
Besides improving density, the other big push with Micron's newest generation of NAND was further improving its throughput. While the company's 232L NAND was built against the ONFi 5.0 specification, which topped out at transfer rates of 2400 MT/sec, their new 276L NAND can hit 3600 MT/sec, which is consistent with the ONFi 5.1 spec.
Meanwhile, the eagle-eyed will likely also pick up on Micron's ninth-generation/G9 branding, which is new to the company. Micron's has not previously used this kind of generational branding for their NAND, which up until now has simply been identified by its layer count (and before the 3D era, its feature size). Internally, this is believed to be Micron's 7th generation 3D NAND architecture. However, taking a page from the logic fab industry, Micron seems to be branding it as ninth-generation in order to keep generational parity with its competitors, who are preparing their own 8th/9th generation NAND (and thus cliam that they are the first NAND maker to ship 9th gen NAND).
And while this NAND will eventually end up in ... SSDs
CXL Gathers Momentum at FMS 2024
The CXL consortium has had a regular presence at FMS (which rechristened itself from 'Flash Memory Summit' to the 'Future of Memory and Storage' this year). Back at FMS 2022, the company had announced v3.0 of the CXL specifications. This was followed by CXL 3.1's introduction at Supercomputing 2023. Having started off as a host to device interconnect standard, it had slowly subsumed other competing standards such as OpenCAPI and Gen-Z. As a result, the specifications started to encompass a wide variety of use-cases by building a protocol on top of the the ubiquitous PCIe expansion bus. The CXL consortium comprises of heavyweights such as AMD and Intel, as well as a large number of startup companies attempting to play in different segments on the device side. At FMS 2024, CXL had a prime position in the booth demos of many vendors.
The migration of server platforms from DDR4 to DDR5, along with the rise of workloads demanding large RAM capacity (but not particularly sensitive to either memory bandwidth or latency), has opened up memory expansion modules as one of the first set of widely available CXL devices. Over the last couple of years, we have had product announcements from Samsung and Micron in this area.
SK hynix CMM-DDR5 CXL Memory Module and HMSDK
At FMS 2024, SK hynix was showing off their DDR5-based CMM-DDR5 CXL memory module with a 128 GB capacity. The company was also detailing their associated Heterogeneous Memory Software Development Kit (HMSDK) - a set of libraries and tools at both the kernel and user levels aimed at increasing the ease of use of CXL memory. This is achieved in part by considering the memory pyramid / hierarchy and relocating the data between the server's main memory (DRAM) and the CXL device based on usage frequency.
The CMM-DDR5 CXL memory module comes in the SDFF form-factor (E3.S 2T) with a PCIe 3.0 x8 host interface. The internal memory is based on 1α technology DRAM, and the device promises DDR5-class bandwidth and latency within a single NUMA hop. As these memory modules are meant to be used in datacenters and enterprises, the firmware includes features for RAS (reliability, availability, and serviceability) along with secure boot and other management features.
SK hynix was also demonstrating Niagara 2.0 - a hardware solution (currently based on FPGAs) to enable memory pooling and sharing - i.e, connecting multiple CXL memories to allow different hosts (CPUs and GPUs) to optimally share their capacity. The previous version only allowed capacity sharing, but the latest version enables sharing of data also. SK hynix had presented these solutions at the CXL DevCon 2024 earlier this year, but some progress seems to have been made in finalizing the specifications of the CMM-DDR5 at FMS 2024.
Microchip and Micron Demonstrate CZ120 CXL Memory Expansion Module
Micron had unveiled the CZ120 CXL Memory Expansion Module last year based on the Microchip SMC 2000 series CXL memory controller. At FMS 2024, Micron and Microchip had a demonstration of the module on a Granite Rapids server.
Additional insights into the SMC 2000 controller were also provided.
The CXL memory controller also incorporates DRAM die failure handling, and Microchip also provides diagnostics and debug tools to analyze failed modules. The memory controller also supports ECC, which forms part of the enterprise... Storage
TSMC's Roadmap at a Glance: N3X, N2P, A16 Coming in 2025/2026 
As announced last week by TSMC, later this year the company is set to start high-volume manufacturing on its N3P fabrication process, and this will be the company's most advanced node for a while. Next year things will get a bit more interesting as TSMC will have two process technologies that could actually compete against each other when they enter high-volume manufacturing (HVM) in the second half of 2025.
| Advertised PPA Improvements of New Process Technologies Data announced during conference calls, events, press briefings and press releases |
|||||||||
| Compiled by AnandTech |
TSMC | ||||||||
| N3 vs N5 |
N3E vs N5 |
N3P vs N3E |
N3X vs N3P |
N2 vs N3E |
N2P vs N3E |
N2P vs N2 |
A16 vs N2P |
||
| Power | -25% -30% |
-34% | -5% -10% |
-7%*** | -25% -30% |
-30% -40% |
-5% -10% |
-15% -20% |
|
| Performance | +10% +15% |
+18% | +5% | +5% Fmax @1.2V** |
+10% +15% |
+15% +20% |
+5 +10% |
+8% +10% |
|
| Density* | ? | 1.3x | 1.04x | 1.10x*** | 1.15x | 1.15x | ? | 1.07x 1.10x |
|
| HVM | Q4 2022 |
Q4 2023 |
H2 2024 |
H2 2025 |
H2 2025 |
H2 2026 |
H2 2026 |
H2 2026 |
|
*Chip density published by TSMC reflects 'mixed' chip density consisting of 50% logic, 30% SRAM, and 20% analog.
**At the same area.
***At the same speed.
The production nodes are N3X (3nm-class, extreme performance-focused) as well as N2 (2nm-class). TSMC says that when compared to N3P, chips made on N3X can either lower power consumption by 7% at the same frequency by lowering Vdd from 1.0V to 0.9V, increase performance by 5% at the same area, or increase transistor density by around 10% at the same frequency. Meanwhile, the key advantage of N3X compared to predecessors is its maximum voltage of 1.2V, which is important for ultra-high-performance applications, such as desktop or datacenter GPUs.
TSMC's N2 will be TSMC's first production node to use gate-all-around (GAA) nanosheet transistors and this will significantly enhance its performance, power, and are... Semiconductors
Not Dead Yet: WD Releases New 6TB 2.5-Inch External Hard Drives - First Upgrade in Seven Years 
UPDATE 5/17, 6 PM: Western Digital has confirmed that the new 2.5-inch T GB HDDs uses 6 SMR platters
The vast majority of laptops nowadays use solid-state drives, which is why the development of new, higher-capacity 2.5-inch hard drives has all but come to a halt. Or rather, it almost has. It seems that the 2.5-inch form factor has a bit more life left in it after all, as today Western Digital has released a slate of new external storage products based on a new, high-capacity 6 TB 2.5-inch hard drive.
WD's new 6 TB spinner is being used to offer upgraded versions of the company's My Passport, Black P10, and and G-DRIVE ArmorATD portable storage products. Notably, however, WD isn't selling the bare 2.5-inch drive on a standalone basis – at least not yet – so for the time being it's entirely reserved for use in external storage.
Consequently, WD isn't publishing much about the 6 TB hard drive itself. The maximum read speed for these products is listed at 130 MB/sec – the same as WD's existing externals – and write performance goes unmentioned.
Notably, all of these 6 TB devices are thicker than their existing 5 TB counterparts, which strongly suggests that WD has increased their storage capacity not by improving their areal density, but by adding another platter to their existing drive platform (which WD has since confirmed). This, in turn, would help to explain why these new drives are being used in external storage products, as WD's 5 TB 2.5-inch drives are already 15mm thick and using 5 platters. 15mm is the highest standard thickness for a 2.5-inch form-factor, and already incompatible with a decent number of portable devices. External drives, in turn, are the only place these even thicker 2.5-inch drives would fit.
WD's specifications also gloss over whether these drives are based on shingled magnetic recording (SMR) technology. The company was already using SMR for their 5 TB drives in order to hit the necessary storage density there, and WD has since confirmed that this is exactly the case. Which is likely why the company isn't publishing write performance specifications for the drives, as we've seen device-managed SMR drives bottom out as low as 10 MB/second in our testing when the drive needs to rewrite data.
Depending on the specific drive model, all of the external storage drives use either a USB-C connector, or the very quaint USB Micro-B 3.0 connector. Though regardless of the physical connector used, all of the drives feature a USB 3.2 Gen 1 (5Gbps) electrical interface, which is more than ample given the drives' physically-limited transfer speeds.
Wrapping things up, according to WD the new drives are available at retail immediately. The WD My Passport Ultra and WD My Passport Ultra for Mac with USB-C both retail for $199.99; the WD My Passport and WD My Passport for Mac are $179.99; the WD My Passport Works With USB-C is $184.99; the gaming-focused WD_Black P10 Game Drive sells for $184.99, and the SanDisk Professional G-Drive ArmorATD is $229.99. All of Western Digital's external storage drives are backed with a three-year limited warranty.
Storage
The vast majority of laptops nowadays use solid-state drives, which is why the development of new, higher-capacity 2.5-inch hard drives has all but come to a halt. Or rather, it almost has. It seems that the 2.5-inch form factor has a bit more life left in it after all, as today Western Digital has released a slate of new external storage products based on a new, high-capacity 6 TB 2.5-inch hard drive.
Kioxia Demonstrates Optical Interface SSDs for Data Centers 
A few years back, the Japanese government's New Energy and Industrial Technology Development Organization (NEDO ) allocated funding for the development of green datacenter technologies. With the aim to obtain up to 40% savings in overall power consumption, several Japanese companies have been developing an optical interface for their enterprise SSDs. And at this year's FMS, Kioxia had their optical interface on display.
For this demonstration, Kioxia took its existing CM7 enterprise SSD and created an optical interface for it. A PCIe card with on-board optics developed by Kyocera is installed in the server slot. An optical interface allows data transfer over long distances (it was 40m in the demo, but Kioxia promises lengths of up to 100m for the cable in the future). This allows the storage to be kept in a separate room with minimal cooling requirements compared to the rack with the CPUs and GPUs. Disaggregation of different server components will become an option as very high throughput interfaces such as PCIe 7.0 (with 128 GT/s rates) become available.
The demonstration of the optical SSD showed a slight loss in IOPS performance, but a significant advantage in the latency metric over the shipping enterprise SSD behind a copper network link. Obviously, there are advantages in wiring requirements and signal integrity maintenance with optical links.
Being a proof-of-concept demonstration, we do see the requirement for an industry-standard approach if this were to gain adoption among different datacenter vendors. The PCI-SIG optical workgroup will need to get its act together soon to create a standards-based approach to this problem.
Storage
![](https://twitter.com/share?url=https://compbuddey.blogspot.com/2025/07/fadus-fc5161-ssd-controller-breaks_29.html&text=Fadu's FC5161 SSD Controller Breaks Cover in Western Digital's PCIe Gen5 Enterprise Drives <p align="center"><a href="https://www.anandtech.com/show/21532/western-digital-uses-fadu-controller-for-pcie-gen5-enterprise-ssds"><img src="https://images.anandtech.com/doci/21532/wdc-sn861-fadu-678_575px.jpg" alt="" /></a></p><p><p>When Western Digital introduced its Ultrastar DC SN861 SSDs earlier this year, the company did not disclose which controller it used for these drives, which made many observers presume that WD was using an in-house controller. But a recent teardown of the drive shows that is not the case; instead, the company is using a controller from Fadu, a South Korean company founded in 2015 that specializes on enterprise-grade turnkey SSD solutions.</p>
<p>The <a href="https://www.westerndigital.com/products/internal-drives/data-center-drives/ultrastar-dc-sn861-ssd?sku=0TS2531">Western Digital Ultrastar DC SN861 SSD</a> is aimed at performance-hungry hyperscale datacenters and enterprise customers which are adopting PCIe Gen5 storage devices these days. And, as uncovered in photos from a <a href="http://www.storagereview.com/review/western-digital-sn861-gen5-ssd-versatile-solutions-for-modern-hyperscale-and-enterprise-needs">recent Storage Review article</a>, the drive is based on <a href="https://www.fadu.io/en/fc5161-gen5/">Fadu's FC5161 NVMe 2.0-compliant controller</a>. The FC5161 utilizes 16 NAND channels supporting an ONFi 5.0 2400 MT/s interface, and features a combination of enterprise-grade capabilities (OCP Cloud Spec 2.0, SR-IOV, up to 512 name spaces for ZNS support, flexible data placement, NVMe-MI 1.2, advanced security, telemetry, power loss protection) not available on other off-the-shelf controllers – or on any previous Western Digital controllers. </p>
<p>The Ultrastar DC SN861 SSD offers sequential read speeds up to 13.7 GB/s as well as sequential write speeds up to 7.5 GB/s. As for random performance, it boasts with an up to 3.3 million random 4K read IOPS and up to 0.8 million random 4K write IOPS. The drives are available in capacities between 1.6 TB and 7.68 TB with one or three drive writes per day (DWPD) over five years rating as well as in U.2 and E1.S form-factors. </p>
<p>While the two form factors of the SN861 share a similar technical design, Western Digital has tailored each version for distinct workloads: the E1.S supports FDP and performance enhancements specifically for cloud environments. By contrast, the U.2 model is geared towards high-performance enterprise tasks and emerging applications like AI.</p>
<p>Without any doubts, Western Digital's Ultrastar DC SN861 is a feature-rich high-performance enterprise-grade SSD. It has another distinctive feature: a 5W idle power consumption, which is rather low by the standards of enterprise-grade drives (e.g., it is 1W lower compared to the SN840). While the difference with predecessors may be just 1W, hyperscalers deploy thousands of drives and for their TCO every watt counts.</p>
<p>Western Digital's Ultrastar DC SN861 SSDs are now available for purchase to select customers (such as Meta) and to interested parties. Prices are unknown, but they will depend on such factors as volumes.</p>
<p>Sources: <a href="https://www.fadu.io/en/fc5161-gen5/">Fadu</a>, <a href="https://www.storagereview.com/review/western-digital-sn861-gen5-ssd-versatile-solutions-for-modern-hyperscale-and-enterprise-needs">Storage Review</a></p>
</p> Storage){kind=link}
![](https://www.pinterest.com/pin/create/button/?url=https://compbuddey.blogspot.com/2025/07/fadus-fc5161-ssd-controller-breaks_29.html&media=https://lh3.googleusercontent.com/blogger_img_proxy/AEn0k_tgQ0CggAKFUKiWdxSuSINhG8Im_TbcNxrQ0srV2G1ISJyuAFDtWu3mwhK5tRrAtEPhNWTqyH7EFmNgm2V44w9WMlsqsVOOTHmK6wvcFxSTkwmZncN6DsD_cLvn1xddzb0pJdNFZyOA&description=Fadu's FC5161 SSD Controller Breaks Cover in Western Digital's PCIe Gen5 Enterprise Drives <p align="center"><a href="https://www.anandtech.com/show/21532/western-digital-uses-fadu-controller-for-pcie-gen5-enterprise-ssds"><img src="https://images.anandtech.com/doci/21532/wdc-sn861-fadu-678_575px.jpg" alt="" /></a></p><p><p>When Western Digital introduced its Ultrastar DC SN861 SSDs earlier this year, the company did not disclose which controller it used for these drives, which made many observers presume that WD was using an in-house controller. But a recent teardown of the drive shows that is not the case; instead, the company is using a controller from Fadu, a South Korean company founded in 2015 that specializes on enterprise-grade turnkey SSD solutions.</p>
<p>The <a href="https://www.westerndigital.com/products/internal-drives/data-center-drives/ultrastar-dc-sn861-ssd?sku=0TS2531">Western Digital Ultrastar DC SN861 SSD</a> is aimed at performance-hungry hyperscale datacenters and enterprise customers which are adopting PCIe Gen5 storage devices these days. And, as uncovered in photos from a <a href="http://www.storagereview.com/review/western-digital-sn861-gen5-ssd-versatile-solutions-for-modern-hyperscale-and-enterprise-needs">recent Storage Review article</a>, the drive is based on <a href="https://www.fadu.io/en/fc5161-gen5/">Fadu's FC5161 NVMe 2.0-compliant controller</a>. The FC5161 utilizes 16 NAND channels supporting an ONFi 5.0 2400 MT/s interface, and features a combination of enterprise-grade capabilities (OCP Cloud Spec 2.0, SR-IOV, up to 512 name spaces for ZNS support, flexible data placement, NVMe-MI 1.2, advanced security, telemetry, power loss protection) not available on other off-the-shelf controllers – or on any previous Western Digital controllers. </p>
<p>The Ultrastar DC SN861 SSD offers sequential read speeds up to 13.7 GB/s as well as sequential write speeds up to 7.5 GB/s. As for random performance, it boasts with an up to 3.3 million random 4K read IOPS and up to 0.8 million random 4K write IOPS. The drives are available in capacities between 1.6 TB and 7.68 TB with one or three drive writes per day (DWPD) over five years rating as well as in U.2 and E1.S form-factors. </p>
<p>While the two form factors of the SN861 share a similar technical design, Western Digital has tailored each version for distinct workloads: the E1.S supports FDP and performance enhancements specifically for cloud environments. By contrast, the U.2 model is geared towards high-performance enterprise tasks and emerging applications like AI.</p>
<p>Without any doubts, Western Digital's Ultrastar DC SN861 is a feature-rich high-performance enterprise-grade SSD. It has another distinctive feature: a 5W idle power consumption, which is rather low by the standards of enterprise-grade drives (e.g., it is 1W lower compared to the SN840). While the difference with predecessors may be just 1W, hyperscalers deploy thousands of drives and for their TCO every watt counts.</p>
<p>Western Digital's Ultrastar DC SN861 SSDs are now available for purchase to select customers (such as Meta) and to interested parties. Prices are unknown, but they will depend on such factors as volumes.</p>
<p>Sources: <a href="https://www.fadu.io/en/fc5161-gen5/">Fadu</a>, <a href="https://www.storagereview.com/review/western-digital-sn861-gen5-ssd-versatile-solutions-for-modern-hyperscale-and-enterprise-needs">Storage Review</a></p>
</p> Storage){kind=link}
![](https://web.whatsapp.com/send?text=Fadu's FC5161 SSD Controller Breaks Cover in Western Digital's PCIe Gen5 Enterprise Drives <p align="center"><a href="https://www.anandtech.com/show/21532/western-digital-uses-fadu-controller-for-pcie-gen5-enterprise-ssds"><img src="https://images.anandtech.com/doci/21532/wdc-sn861-fadu-678_575px.jpg" alt="" /></a></p><p><p>When Western Digital introduced its Ultrastar DC SN861 SSDs earlier this year, the company did not disclose which controller it used for these drives, which made many observers presume that WD was using an in-house controller. But a recent teardown of the drive shows that is not the case; instead, the company is using a controller from Fadu, a South Korean company founded in 2015 that specializes on enterprise-grade turnkey SSD solutions.</p>
<p>The <a href="https://www.westerndigital.com/products/internal-drives/data-center-drives/ultrastar-dc-sn861-ssd?sku=0TS2531">Western Digital Ultrastar DC SN861 SSD</a> is aimed at performance-hungry hyperscale datacenters and enterprise customers which are adopting PCIe Gen5 storage devices these days. And, as uncovered in photos from a <a href="http://www.storagereview.com/review/western-digital-sn861-gen5-ssd-versatile-solutions-for-modern-hyperscale-and-enterprise-needs">recent Storage Review article</a>, the drive is based on <a href="https://www.fadu.io/en/fc5161-gen5/">Fadu's FC5161 NVMe 2.0-compliant controller</a>. The FC5161 utilizes 16 NAND channels supporting an ONFi 5.0 2400 MT/s interface, and features a combination of enterprise-grade capabilities (OCP Cloud Spec 2.0, SR-IOV, up to 512 name spaces for ZNS support, flexible data placement, NVMe-MI 1.2, advanced security, telemetry, power loss protection) not available on other off-the-shelf controllers – or on any previous Western Digital controllers. </p>
<p>The Ultrastar DC SN861 SSD offers sequential read speeds up to 13.7 GB/s as well as sequential write speeds up to 7.5 GB/s. As for random performance, it boasts with an up to 3.3 million random 4K read IOPS and up to 0.8 million random 4K write IOPS. The drives are available in capacities between 1.6 TB and 7.68 TB with one or three drive writes per day (DWPD) over five years rating as well as in U.2 and E1.S form-factors. </p>
<p>While the two form factors of the SN861 share a similar technical design, Western Digital has tailored each version for distinct workloads: the E1.S supports FDP and performance enhancements specifically for cloud environments. By contrast, the U.2 model is geared towards high-performance enterprise tasks and emerging applications like AI.</p>
<p>Without any doubts, Western Digital's Ultrastar DC SN861 is a feature-rich high-performance enterprise-grade SSD. It has another distinctive feature: a 5W idle power consumption, which is rather low by the standards of enterprise-grade drives (e.g., it is 1W lower compared to the SN840). While the difference with predecessors may be just 1W, hyperscalers deploy thousands of drives and for their TCO every watt counts.</p>
<p>Western Digital's Ultrastar DC SN861 SSDs are now available for purchase to select customers (such as Meta) and to interested parties. Prices are unknown, but they will depend on such factors as volumes.</p>
<p>Sources: <a href="https://www.fadu.io/en/fc5161-gen5/">Fadu</a>, <a href="https://www.storagereview.com/review/western-digital-sn861-gen5-ssd-versatile-solutions-for-modern-hyperscale-and-enterprise-needs">Storage Review</a></p>
</p> Storage | https://compbuddey.blogspot.com/2025/07/fadus-fc5161-ssd-controller-breaks_29.html){kind=link}
![](mailto:?subject=Fadu's FC5161 SSD Controller Breaks Cover in Western Digital's PCIe Gen5 Enterprise Drives <p align="center"><a href="https://www.anandtech.com/show/21532/western-digital-uses-fadu-controller-for-pcie-gen5-enterprise-ssds"><img src="https://images.anandtech.com/doci/21532/wdc-sn861-fadu-678_575px.jpg" alt="" /></a></p><p><p>When Western Digital introduced its Ultrastar DC SN861 SSDs earlier this year, the company did not disclose which controller it used for these drives, which made many observers presume that WD was using an in-house controller. But a recent teardown of the drive shows that is not the case; instead, the company is using a controller from Fadu, a South Korean company founded in 2015 that specializes on enterprise-grade turnkey SSD solutions.</p>
<p>The <a href="https://www.westerndigital.com/products/internal-drives/data-center-drives/ultrastar-dc-sn861-ssd?sku=0TS2531">Western Digital Ultrastar DC SN861 SSD</a> is aimed at performance-hungry hyperscale datacenters and enterprise customers which are adopting PCIe Gen5 storage devices these days. And, as uncovered in photos from a <a href="http://www.storagereview.com/review/western-digital-sn861-gen5-ssd-versatile-solutions-for-modern-hyperscale-and-enterprise-needs">recent Storage Review article</a>, the drive is based on <a href="https://www.fadu.io/en/fc5161-gen5/">Fadu's FC5161 NVMe 2.0-compliant controller</a>. The FC5161 utilizes 16 NAND channels supporting an ONFi 5.0 2400 MT/s interface, and features a combination of enterprise-grade capabilities (OCP Cloud Spec 2.0, SR-IOV, up to 512 name spaces for ZNS support, flexible data placement, NVMe-MI 1.2, advanced security, telemetry, power loss protection) not available on other off-the-shelf controllers – or on any previous Western Digital controllers. </p>
<p>The Ultrastar DC SN861 SSD offers sequential read speeds up to 13.7 GB/s as well as sequential write speeds up to 7.5 GB/s. As for random performance, it boasts with an up to 3.3 million random 4K read IOPS and up to 0.8 million random 4K write IOPS. The drives are available in capacities between 1.6 TB and 7.68 TB with one or three drive writes per day (DWPD) over five years rating as well as in U.2 and E1.S form-factors. </p>
<p>While the two form factors of the SN861 share a similar technical design, Western Digital has tailored each version for distinct workloads: the E1.S supports FDP and performance enhancements specifically for cloud environments. By contrast, the U.2 model is geared towards high-performance enterprise tasks and emerging applications like AI.</p>
<p>Without any doubts, Western Digital's Ultrastar DC SN861 is a feature-rich high-performance enterprise-grade SSD. It has another distinctive feature: a 5W idle power consumption, which is rather low by the standards of enterprise-grade drives (e.g., it is 1W lower compared to the SN840). While the difference with predecessors may be just 1W, hyperscalers deploy thousands of drives and for their TCO every watt counts.</p>
<p>Western Digital's Ultrastar DC SN861 SSDs are now available for purchase to select customers (such as Meta) and to interested parties. Prices are unknown, but they will depend on such factors as volumes.</p>
<p>Sources: <a href="https://www.fadu.io/en/fc5161-gen5/">Fadu</a>, <a href="https://www.storagereview.com/review/western-digital-sn861-gen5-ssd-versatile-solutions-for-modern-hyperscale-and-enterprise-needs">Storage Review</a></p>
</p> Storage&body=https://compbuddey.blogspot.com/2025/07/fadus-fc5161-ssd-controller-breaks_29.html){kind=link}
Realtek Outlines SSD Controller Roadmap: High-End PCIe 5.0 x4 Platform in the Works 
While Realtek is best known in the enthusiast space for for its peripheral controllers such as audio codecs and network controllers, the company also has a small-but-respectable SSD controller business that tends to fly under the radar due to its focus on entry-level and mainstream drives. But Realtek's stature in the SSD space is on the rise, as the company is not only planning new PCIe Gen5 SSD controllers, but also their first high-end, DRAM-equipped SSD controller.
For this year's Computex trade show, Realtek laid out a new SSD controller roadmap that calls for the company to release a trio of new SSD controllers over the next couple of years. First up is a new four-channel entry-level PCIe 4.0 controller, the RTS5776DL, which will be joined a bit later by a PCIe 5.0 variant, the RTS5781DL. But most interesting on Realtek's new roadmap is the final chip being planned: the eight-channel, DRAM-equipped RTS5782, which would be the company's first high-end SSD controller, capable of hitting sequential read rates as high as 14GB/second.
| Realtek NVMe SSD Controller Comparison | |||||||||
| RTS5782 | RTS5781DL | RTS5776DL | RTS5772DL | RTS5766DL | |||||
| Market Segment | High-End | Mainstream | Entry-Level | ||||||
| Error Correction | 4K LDPC | 2K LDPC | |||||||
| DRAM | DDR4, LPDDR4(X) | No | No | No | No | ||||
| Host Interface | PCIe 5.0 x4 | PCIe 5.0 x4 | PCIe 4.0 x4 | PCIe 4.0 x4 | PCIe 3.0 x4 | ||||
| NVMe Version | NVMe 2.0 | NVMe 2.0 | NVMe 2.0 | NVMe 1.4 | NVMe 1.4 | ||||
| NAND Channels, Interface Speed | 8 ch, 3600 MT/s |
4 ch, 3600 MT/s |
4 ch, 3600 MT/s |
8 ch, 1600 MT/s |
4 ch, 1200 MT/s |
||||
| Sequential Read | 14 GB/s | 10 GB/s | 7.4 GB/s | 6 GB/s | 3.2 GB/s | ||||
| Sequential Write | 12 GB/s | 10 GB/s | 7.4 GB/s | 6 GB/s | 2.2 GB/s | ||||
| 4KB Random Read IOPS | 2500k | 1400k | 1200k | - | - | ||||
| 4KB Random Write IOPS | 2500k | 1400k | 1200k | - | - | ||||
Diving a bit deeper into Realtek's roadmap, the RTS5776DL is traditional DRAM-less PCIe Gen4 x4 controller with four NAND chann... SSDs
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Kioxia Details BiCS 8 NAND at FMS 2024: 218 Layers With Superior Scaling
Kioxia's booth at FMS 2024 was a busy one with multiple technology demonstrations keeping visitors occupied. A walk-through of the BiCS 8 manufacturing process was the first to grab my attention. Kioxia and Western Digital announced the sampling of BiCS 8 in March 2023. We had touched briefly upon its CMOS Bonded Array (CBA) scheme in our coverage of Kioxial's 2Tb QLC NAND device and coverage of Western Digital's 128 TB QLC enterprise SSD proof-of-concept demonstration. At Kioxia's booth, we got more insights.
Traditionally, fabrication of flash chips involved placement of the associate logic circuitry (CMOS process) around the periphery of the flash array. The process then moved on to putting the CMOS under the cell array, but the wafer development process was serialized with the CMOS logic getting fabricated first followed by the cell array on top. However, this has some challenges because the cell array requires a high-temperature processing step to ensure higher reliability that can be detrimental to the health of the CMOS logic. Thanks to recent advancements in wafer bonding techniques, the new CBA process allows the CMOS wafer and cell array wafer to be processed independently in parallel and then pieced together, as shown in the models above.
The BiCS 8 3D NAND incorporates 218 layers, compared to 112 layers in BiCS 5 and 162 layers in BiCS 6. The company decided to skip over BiCS 7 (or, rather, it was probably a short-lived generation meant as an internal test vehicle). The generation retains the four-plane charge trap structure of BiCS 6. In its TLC avatar, it is available as a 1 Tbit device. The QLC version is available in two capacities - 1 Tbit and 2 Tbit.
Kioxia also noted that while the number of layers (218) doesn't compare favorably with the latest layer counts from the competition, its lateral scaling / cell shrinkage has enabled it to be competitive in terms of bit density as well as operating speeds (3200 MT/s). For reference, the latest shipping NAND from Micron - the G9 - has 276 layers with a bit density in TLC mode of 21 Gbit/mm2, and operates at up to 3600 MT/s. However, its 232L NAND operates only up to 2400 MT/s and has a bit density of 14.6 Gbit/mm2.
It must be noted that the CBA hybrid bonding process has advantages over the current processes used by other vendors - including Micron's CMOS under array (CuA) and SK hynix's 4D PUC (periphery-under-chip) developed in the late 2010s. It is expected that other NAND vendors will also move eventually to some variant of the hybrid bonding scheme used by Kioxia.
Storage
Micron Ships Denser & Faster 276 Layer TLC NAND, Arriving First In Micron 2650 Client SSDs
Micron on Tuesday announced that the company has begun shipping its 9th Generation (G9) 276 layer TLC NAND. The next generation of NAND from the prolific memory maker, Micron's latest NAND is designed to further push the envelope on TLC NAND performance, offering significant density and performance improvements over its existing NAND technology.
Micron's G9 TLC NAND memory features 276 active layers, which is up from 232-layers in case of Micron's previous generation TLC NAND. At this point the company is being light on technical details in their official material. However in a brief interview with Blocks & Files, the company confirmed that their 276L NAND still uses a six plane architecture, which was first introduced with the 232L generation. At this point we're assuming Micron is also string-stacking two decks of NAND together, as they have been for the past couple of generations, which means we're looking at 138 layer decks.
| Micron TLC NAND Flash Memory | |||
| 276L | 232L (B58R) |
176L (B47R) |
|
| Layers | 276 | 232 | 176 |
| Decks | 2 (x138)? | 2 (x116) | 2 (x88) |
| Die Capacity | 1 Tbit | 1 Tbit | 512 Gbit |
| Die Size (mm2) | ~48.9mm2 | ~70.1mm2 | ~49.8mm2 |
| Density (Gbit/mm2) | ~21 | 14.6 | 10.3 |
| I/O Speed | 3.6 GT/s (ONFi 5.1) |
2.4 GT/s (ONFi 5.0) |
1.6 GT/s (ONFI 4.2) |
| Planes | 6 | 6 | 4 |
| CuA / PuC | Yes | Yes | Yes |
On the density front, Micron told Blocks & Files that they have improved their NAND density by 44% over their 232L generation. Which, given what we know about that generation, would put the density at around 21 Gbit/mm2. Or for a 1Tbit die of TLC NAND, that works out to a die size of roughly 48.9mm2, comparable to the die size of a 512Gbit TLC die from Micron's older 176L NAND.
Besides improving density, the other big push with Micron's newest generation of NAND was further improving its throughput. While the company's 232L NAND was built against the ONFi 5.0 specification, which topped out at transfer rates of 2400 MT/sec, their new 276L NAND can hit 3600 MT/sec, which is consistent with the ONFi 5.1 spec.
Meanwhile, the eagle-eyed will likely also pick up on Micron's ninth-generation/G9 branding, which is new to the company. Micron's has not previously used this kind of generational branding for their NAND, which up until now has simply been identified by its layer count (and before the 3D era, its feature size). Internally, this is believed to be Micron's 7th generation 3D NAND architecture. However, taking a page from the logic fab industry, Micron seems to be branding it as ninth-generation in order to keep generational parity with its competitors, who are preparing their own 8th/9th generation NAND (and thus cliam that they are the first NAND maker to ship 9th gen NAND).
And while this NAND will eventually end up in ... SSDs
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