Kioxia CM6-V 6.4TB Enterprise SSD Review

Kioxia's CM6 was the first Gen 4 Enterprise SSD on the scene and it is likely the best-mixed workload performer to date.

@JonCoulterSSD
Published Sun, Aug 29 2021 7:05 PM CDT   |   Updated Mon, Aug 30 2021 8:32 PM CDT
Rating: 100%Manufacturer: KIOXIA (KCM6XVUL6T40)

Introduction and Drive Details

Kioxia (formerly Toshiba) was the first to market with PCIe Gen4 enterprise SSDs, or at least that's how we remember it going by 2019 Flash Memory Summit recollection. Fast forward to today, two years later, and we've finally gotten our chance to see firsthand what PCIe Gen4 looks like as served up Kioxia style. We've already taken Intel's newest PCIe Gen4 P5510 Enterprise SSD for a spin and seen for ourselves what double the bandwidth can bring to the datacenter as well as SMB's.

Obviously, as the second-largest producer of NAND on the planet, the CM6 is arrayed with Kioxia's 96layer BiCS4 flash. BiCS4 96Layer TLC Flash has been around for going on three years now, and although we've seen others bring to market newer flash with higher layer counts, we've not seen any that can deliver real-world performance that can match good ole Kioxia BiCS 4. We've observed this truth in the consumer space where our real-world performance leaders have one thing in common, and that's BiCs 4 flash arrays. Now we will demonstrate this happening in the enterprise space as well. Remember, it's not about sequential speeds, nor is it about 8K random performance at QD256. It's really about how well an SSD can put it all together and deliver real performance where it matters most.

Quick Specs/Comparison Products

Kioxia CM6-V 6.4TB Enterprise SSD Review 01 | TweakTown.com
VIEW GALLERY - 29 IMAGES

Kioxia CM6-V Enterprise PCIe Gen4 x4 NVMe SSD

Kioxia CM6-V 6.4TB Enterprise SSD Review 02 | TweakTown.com

This side of the drive features a familiar-looking manufacturer label.

Kioxia CM6-V 6.4TB Enterprise SSD Review 03 | TweakTown.com

The bottom of the drive's enclosure is a heavy-duty cast aluminum piece that serves as a heat sink.

Specifications and Features

Kioxia CM6-V 6.4TB Enterprise SSD Review 04 | TweakTown.com

Kioxia's CM6 is a PCIe Gen4 x4 NVMe SSD is a 2.5" x 15mm U.2 (SFF-8639) Enterprise SSD available in capacities ranging from 800GB up to 12.8TB. Features include a PCIe Gen4 x4 U.2 interface, Kioxia NVMe controller, BiCS4 TLC flash, dual-port access, power loss protection, multiple name spaces, end-to-end data protection featuring advanced proprietary bit correction on memories in the data path for protection at every layer. Endurance is stellar at three drive writes per day for 5-years.

Current online pricing finds the 6.4 CM6-V 6.4TB retailing for approximately $2500.

Enterprise Testing Methodology

TweakTown strictly adheres to industry-accepted Enterprise Solid State Storage testing procedures. Each test we perform repeats the same sequence of the following four steps:

  1. Secure Erase SSD
  2. Write entire capacity of SSD a minimum of 2x with 128KB sequential write data, seamlessly transition to next step
  3. Precondition SSD at maximum QD measured (QD32 for SATA, QD256 for PCIe) with the test specific workload for a sufficient amount of time to reach a constant steady-state, seamlessly transition to next step
  4. Run test specific workload for 5-minutes at each measured Queue Depth, record results

Benchmarks - Random and Sequential Performance

4K Random Write/Read

Kioxia CM6-V 6.4TB Enterprise SSD Review 05 | TweakTown.com

We precondition the drive for 16,000 seconds, receiving performance data every second. We plot this data to observe the test subject's descent into steady-state.

Steady-state is achieved at 8,000 seconds of preconditioning. The average steady-state write performance at QD256 is approximately 330K IOPS. The relatively tight pattern with virtually no outliers indicates a high QoS.

Kioxia CM6-V 6.4TB Enterprise SSD Review 06 | TweakTown.com
Kioxia CM6-V 6.4TB Enterprise SSD Review 07 | TweakTown.com

We have no problem sustaining 335,000 4K random write IOPS which is 15K better than the stated sustained random write spec. At every measured queue depth, the CM6-V is outperforming its competition by a significant margin. Impressive.

Kioxia CM6-V 6.4TB Enterprise SSD Review 08 | TweakTown.com
Kioxia CM6-V 6.4TB Enterprise SSD Review 09 | TweakTown.com

The datasheet for the CM6-V states random 4K read performance of up to 1,400,000 IOPS. We only measure to queue depths of 256, which is likely the reason we are topping out at 1.21 million IOPS. Intel's P5510 outperforms the CM6-V at queue depths of up to 64, then the CM6-V pulls away in this pure random test. Intel's new 144Layer flash has the advantage in pure 4K random read performance at low queue depths.

8K Random Write/Read

Kioxia CM6-V 6.4TB Enterprise SSD Review 10 | TweakTown.com

We precondition the drive for 16,000 seconds, receiving performance data every second. We plot this data to observe the test subject's descent into steady-state.

Steady-state is achieved at 9,000 seconds of preconditioning. The average steady-state write performance at QD256 is approximately 168K IOPS.

Kioxia CM6-V 6.4TB Enterprise SSD Review 11 | TweakTown.com
Kioxia CM6-V 6.4TB Enterprise SSD Review 12 | TweakTown.com

We expect 8K random to track exactly the same as 4K random, just at a 50% lower rate. The CM6-V performs as expected. Low queue depth performance is phenomenal, certainly the best we've seen from a flash-based datacenter SSD. Performance that matters.

Kioxia CM6-V 6.4TB Enterprise SSD Review 13 | TweakTown.com
Kioxia CM6-V 6.4TB Enterprise SSD Review 14 | TweakTown.com

Here the CM6-V takes charge at QD32 and proceeds to lay waste to the competition as queue depths increase. We are seeing a mind-blowing 756,000 8K random read IOPS at QD256. Wow. Again, Intel's 144L flash has the advantage at lower queue depths when the workload is pure 8K random read.

128K Sequential Write/Read

Kioxia CM6-V 6.4TB Enterprise SSD Review 15 | TweakTown.com

We precondition the drive for 6,500 seconds, receiving performance data every second. Steady-state for this test was already achieved when we filled the drive with 128K seq data. The nice, tight pattern we are seeing indicates a high QoS. Excellent.

The average steady-state sequential write performance at QD256 is approximately 4,000 MB/s.

Kioxia CM6-V 6.4TB Enterprise SSD Review 16 | TweakTown.com
Kioxia CM6-V 6.4TB Enterprise SSD Review 17 | TweakTown.com

Our testing indicates factory sequential write specifications to spot on. More impressive, however, is that the CM6-V can deliver its max sustained write performance at QD1. Amazing really.

Kioxia CM6-V 6.4TB Enterprise SSD Review 18 | TweakTown.com
Kioxia CM6-V 6.4TB Enterprise SSD Review 19 | TweakTown.com

Again, factory specs are spot on. 6,900 MB/s is head-turning sequential performance, but we are more impressed with how the CM6-V gets there. Look at that performance curve. It's exactly what we want to see. Look at how inferior the performance curve of the Gen4 P5510 is. Intel's P5510 can deliver a little more at queue depths above 64, but it doesn't even swing into action until QD32. As we see it, this is a big win for the CM6-V.

Benchmarks - Server Workloads

Email Server

An Email Server workload is a demanding 8K test with a 50 percent R/W distribution. This application gives a good indication of how well a drive will perform in a write-heavy workload environment.

Kioxia CM6-V 6.4TB Enterprise SSD Review 20 | TweakTown.com

We precondition the drive for 16,000 seconds, receiving performance data every second. We plot this data to observe the test subject's descent into steady-state.

Steady-State is achieved at approximately 9,000 seconds of preconditioning. The average steady-state workload performance at QD256 is approximately 300K IOPS. Impressive is an understatement.

Our data patterns again indicate high QoS.

Kioxia CM6-V 6.4TB Enterprise SSD Review 21 | TweakTown.com
Kioxia CM6-V 6.4TB Enterprise SSD Review 22 | TweakTown.com

This chart demonstrates exactly why we believe Kioxia BiCS4 flash is the real-world performance leader. We see it in consumer SSDs, and now we see it on the enterprise front. This is real performance where it matters, not something purely synthetic like the previous tests we ran. Performance that matters and performance without equal where it matters most is what the CM6-V is dishing out.

OLTP/Database Server

An Online Transaction Processing (OLTP) / Database workload is a demanding 8K test with a 66/33 percent R/W distribution. OLTP is online processing of financial transactions and high-frequency trading.

Kioxia CM6-V 6.4TB Enterprise SSD Review 23 | TweakTown.com

We precondition the drive for 16,000 seconds, receiving performance data every second. We plot this data to observe the test subject's descent into steady-state.

Steady-state is achieved at 11,000 seconds of preconditioning. The average steady-state workload performance at QD256 is a lofty 360K IOPS.

QoS is indicated as excellent.

Kioxia CM6-V 6.4TB Enterprise SSD Review 24 | TweakTown.com
Kioxia CM6-V 6.4TB Enterprise SSD Review 25 | TweakTown.com

As stunning as its Email Server performance is, its OLTP/Database performance is even better. We have competition in name only because the CM6-V has no flash-based competition, at least not in our test pool. Real performance where it matters.

Web Server

A Web Server workload is a pure random read test with a wide range of file sizes, ranging from 512B to 512KB at varying percentage rates per file size.

Kioxia CM6-V 6.4TB Enterprise SSD Review 26 | TweakTown.com

We precondition the drive for 16,000 seconds, receiving performance data every second. We plot this data to observe the test subject's descent into steady-state.

We precondition for this test with an inverted (all-write) workload, so no relevant information can be gleaned from this preconditioning.

Kioxia CM6-V 6.4TB Enterprise SSD Review 27 | TweakTown.com
Kioxia CM6-V 6.4TB Enterprise SSD Review 28 | TweakTown.com

Intel's P5510 comes out on top at queue depths of more than 32. However, we see that as too little too late and give the win to the CM6-V because it maintains a small lead with this difficult pure read workload in the typical operating range.

Final Thoughts

The CM6-V was the first Gen4 enterprise SSD, and it has shown itself to be the best to date. This is quite amazing and serves to cement our belief that Kioxia BiCS4 96L TLC is the best performing common flash currently employed on any SSD, whether they be consumer or enterprise like the drive we tested today. Other flash can reach higher speeds but cannot match BiCS 4, where the rubber meets the road.

Kioxia CM6-V 6.4TB Enterprise SSD Review 29 | TweakTown.com

What's the best performing flash-based enterprise SSD we've ever tested? That's easy. It is Kioxia's mighty CM6-V. Not only is it by far the best performer, but it is also the most enduring we've seen to date. ROI without equal. Impressive in every way, the Kioxia CM6-V has earned TweakTown's highest award.

Pros:

  • Endurance
  • PCIe Gen4
  • Dual Port
  • Capacity Options

Cons:

  • Nothing
Buy at Amazon

Performance

100%

Quality

100%

Features

100%

Value

100%

Overall

100%

The Bottom Line

Kioxia's CM6-V sets the standard for datacenter SSDs.

TweakTown award
100%

Kioxia CM6-V 6.4TB NVMe PCIe Gen4 x4 SSD

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* Prices last scanned on 9/15/2021 at 8:48 pm CDT - prices may not be accurate, click links above for the latest price. We may earn an affiliate commission.

Jon joined the TweakTown team in 2013 and has since reviewed 100s of new storage products. Jon became a computer enthusiast when Windows XP launched. He was into water cooling and benching ATI video cards with modded drivers. Jon has been building computers for others for more than 10 years. Jon became a storage enthusiast the day he first booted an Intel X25-M G1 80GB SSD. Look for Jon to bring consumer SSD reviews into the spotlight.

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