256GB Class Performance Testing
The new 250GB SN500 doesn't stand up very well against similarly priced models shipping today. Prices have fallen so low that the window between premium SATA and premium NVMe is really just a sliver compared to what it was last year with 256GB class models. We expect to see the SN500 price to shrink over time, as with all new SSDs. That hasn't happened just yet with this new release, but the other drives in this review have all hit record lows.
Sequential Read Performance
The new WD Blue SN500 NVMe delivers similar sequential read performance that we found in other purpose-built entry-level and mainstream SSDs. The PCIe x2 interface doesn't allow the drive to reach the same sequential levels as the drives with twice the available bandwidth.
Sequential Write Performance
We can say the same when it comes to large block size sequential writes. The SN500 delivers better than expected sequential write performance. The small number of flash die limit the write performance of modern 256GB SSDs. We point to the SN500 outperforming the Intel SSD 760p (with a x4 lane interface) and use the results to show how efficient BiCS FLASH can be.
Sustained Sequential Write Performance
The 250GB SN500 uses a relatively small SLC buffer size compared to many of the new controller designs with dynamic buffers. The cache is large enough for incoming random data but doesn't do a lot for your large block size files, like movies and music. The native TLC write performance is just over 400 MB/s, around 100 MB/s higher than many other SSDs in this capacity.
Random Read Performance
Of the drives tested for the charts today, the 250GB SN500 delivers the lowest random read performance. At QD1, the drive doesn't hit 8,000 IOPS and that's unfortunate in a world where mainstream SATA SSDs surpass 11,000 IOPS at the same queue depth.
Random Write Performance
We asked a WD representative about host memory buffer technology and were surprised to learn the drive doesn't use this technology. The drive still performs well in small block size random data writes. It performs much better than we expected, but we do foresee some issues with mixed random workloads without the technology.
70% Read Sequential Performance
Despite its interface disadvantage, the SN500 delivers strong sequential mixed read and write performance. The drive outperformed nearly every other drive on the chart other than the MyDigitalSSD BPX Pro with a similar controller architecture.
70% Read Random Performance
The weak random read performance is difficult to overcome in the mixed test with 70% reads. At lower queue depths, the SN500 is in line with the other mainstream NVMe SSDs on the chart.
Last updated: Sep 25, 2019 at 12:28 am CDT
- Page 1 [Introduction, Specifications, and Pricing]
- Page 2 [256GB Class Performance Testing]
- Page 3 [256GB Class Real-World Performance Testing]
- Page 4 [Final Thoughts]