We already declared the end of SATA SSDs for enthusiasts, but the assault has trickled down to the mainstream. With deep price cuts to existing products, there is only a sliver of space for a company to bring up a mainstream NVMe SSD, and we think WD hit the target.
On the technical side, there are only two paths to make a mainstream NVMe SSD today. The first we've seen from Intel and Crucial. Both companies used 4-bit per cell memory on the SSD 660P and P1. There products results are what we expected. Crucial has a DRAM wing in the company and managed to undercut Intel's pricing on a similar product because Intel's doesn't have the luxury of in-house DRAM.
Western Digital doesn't have an in-house DRAM manufacturing business but still wants a mainstream NVMe SSD to compliment the premium Black SN750 NVMe. Instead of increasing the BOM cost to purchase DRAM, the company simply found a way to do without the expensive component. This brings us to the second way to make a profitable mainstream NVMe SSD today, go DRAMless.
To keep costs down and to focus on the mainstream, the new WD Blue SN500 NVMe SSD only ships in two capacities, 250GB and 500GB.
Both drives deliver a maximum sequential read speed of 1,700 MB/s and write sequential data between 1,300 MB/s (250GB model) and 1,450 MB/s (500GB model). The performance is roughly three times higher than the WD Blue 3D SATA SSD introduced last year.
The new Blue SN500 NVMe also delivers significantly more random performance over the model released a year ago. The new NVMe series delivers between 210,000 and 275,000 random read IOPS performance. Random writes reach as high as 300,000 thanks to the single-level cell write buffer in Western Digital's BiCS FLASH memory.
The performance comes from a custom WD controller that first started development under SanDisk before the acquisition. The PCIe 3.0 x2 controller uses a DRAMless design, but it does not take advantage of Host Memory Buffer technology (HMB) to increase performance. HMB uses a small amount of system memory to cache the SSD's table map and is all but standard now for DRAMless NVMe SSDs.
Pricing, Warranty, and Endurance
WD hit a strong balance between performance and cost with the Blue SN500 NVMe Series. The 250GB model starts the series out at just $54.99. The larger 500GB model reaches just $77.99. Both capacities carry an impressive 5-year warranty that we usually find reserved for premium models.
The Blue SN500 endurance is the weakest part of the warranty. The series includes just 150 TBW for the 250GB drive, but that does double to 300 TBW on the larger model.
A Closer Look
WD stuffs all of the components in a small section of the drive. There are only two main packages, the controller and the flash.