Technology & Positioning
The WD Black SN7100 is the company's new high-end value drive, taking over that spot from the SN770, which was released in 2022—three years ago. While some drives on the market are PCI-Express 5.0, the SN7100 is Gen 4, which is not a huge deal, as long as performance is good, and it should help keep the heat output low, too. The NAND flash is the very recently released 218-layer BiCS8 TLC flash (the SN770 was built using 112-layer BiCS5). As expected, you get a new controller, too, the WD A101 "Polaris 3" has been designed for DRAM-less operation with HMB support. Other details aren't known about the controller, other than it's a 4-channel design.

The component selection choices on the SN7100 mean that all major pieces of the drive are made by WD/Kioxia, a unique capability also possessed by Samsung and Micron/Crucial. This allows these companies to bypass supply-chain challenges, align R&D efforts more closely, and achieve better pricing than manufacturers who must source their components externally.

Synthetic Performance
Synthetic performance results of the SN7100 are very good, especially considering its positioning. In many tests the drive beats high-end DRAM-based drives and is generally near the top of the charts. Random write is a bit lower, which is expected for a DRAM-less drive, but the numbers are not much worse than more expensive drives with DRAM. An interesting result is fSync QD1, which is important for databases and other enterprise applications. After sending each write to the drive, an fSync command is issued, which tells the drive "save everything to flash, and wait until that is stored safely." This capability is important to safeguard critical data and ensure consistency during power outages and system crashes. Here, the SN7100 achieves a new record score, the best result we ever recorded, by a big margin. I suspect that the drive really ignores fSync, which means it shouldn't be used with software that relies on fSync. Anyone know how to verify this? Reach out to me.

Real-life Performance
Performance results in our real-life testing are even more impressive. We are running real applications, not traces, and the drives are filled to 85% of their capacity, reflecting real-world conditions. Here the SN7100 is around 6% faster than the WD Black SN770 and is able to outperform every single PCIe Gen 4 drive in our test group. It's 2% faster than the legendary MAP1602 drives like Lexar NM790. It also beats Samsung 990 Pro by 2%. Very impressive for a DRAM-less drive. The only SSD that's faster is the PCI-Express 5.0 Corsair MP700 Pro, which has a tiny 1% lead. Real application and games don't need huge sequential transfer rates of over 10 GB/s—in a typical consumer PC, most activity is random read and write at low queue depth, mostly QD1.

SLC Cache
WD's drive comes with an SLC cache size of 95%, or 648 GB, which means it will fill nearly the whole capacity in SLC mode first, which lets it absorb even the biggest bursts of write active. Once the cache is full, the drive will move data from SLC into TLC in the background, when it's sitting idle, or when it needs more space for incoming data. Filling the drive's whole 2 TB capacity completed at 1 GB/s, which is better than most DRAM-less SSDs. The MAP1602-based drives get around 1.4 GB/s, the best high-end drives on the market reach well over 2 GB/s. This is the only weak point of the SN7100. If you expect to write A LOT of data in a short time, and speed matters, then you might want to consider more expensive alternatives.

Thermals & Energy Efficiency
Thermal performance of the SN7100 is excellent. Even the naked drive without any heatsink will not throttle during normal usage. Only when heavily loaded for a long time, writing hundreds of GB in that time, there will be a bit of throttling. Considering how rare these workloads are, it's fine to run the drive without a heatsink. If you plop any small M.2 heatsink on the drive then there won't be any throttling at all. This is extremely impressive, as it makes SSD cooling a complete non-issue.

How is that possible? WD's new controller is the answer. It's a highly energy-efficient design that uses very little power when moving data around. The SN7100 is actually the most efficient SSD we ever tested—for both reads and writes. Idle power draw is ok, it could be a little bit lower, but close enough. Just like all other WD drives we ever tested, idle power draw in a mobile scenario is very high, because the drive never enters its lowest ASPM power state—no idea why, all the other drives go into this state correctly. I've noticed this in many WD reviews, but even WD couldn't provide a proper answer. I'm assuming that in a real laptop, the drive will be able to reach the low power state properly.

Pricing & Alternatives
The WD Black SN7100 2 TB is currently listed online for $140, which is a pretty good price for such an awesome 2 TB SSD. Strong competition comes from the various MAP1062 drives like the Lexar NM790 ($145), WD's own SN770 ($120) and Crucial T500 ($145). As you can see, WD priced their SSD only a tiny bit cheaper than the alternatives, which isn't unreasonable for a new release with such impressive performance characteristics. If you can live with slightly lower performance, then drives like the Team Group G50 ($105), WD SN580 ($110) and similar disks in that price range could be alternatives. Still, for me the SN7100 is the best SSD on the market, thanks to its great performance paired with outstanding efficiency at a very competitive price point. It's a shame that there is no 4 TB variant though, since a lot of people are starting to look for capacities beyond 2 TB.