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WD Black SN850 1TB SSD Review

CrystalDiskMark is a useful benchmark to measure theoretical performance levels of hard drives and SSDs. We are using v7.0.

In the CrystalDiskMark v6.0.2 4K QD32 test the WD Black SN850 sits in second place behind Patriot’s VP4100 drive. Using this benchmark we could confirm the official 7,000MB/s Sequential read figure with a test result of 7,022MB/s. However, the write result of 5,188MB/s is a little short of the official 5,300MB/s.

Comparing the two result screens it appears that the WD Black G2 controller doesn’t have a preference when it comes to the type of data it’s being asked to handle.




The latest version of CrystalDiskMark, version 7, includes a couple of profiles that can be used for testing – Peak Performance and Real World. The result screens for these two profiles not only display MB/s results but also IOPS and latency.

Looking at the results for Sequential read/write performance we could confirm both official Sequential performance figures. The drive is rated up to 7,000MB/s for reads, with the tested drive producing 7,071MB/s and up to 5,300MB/s for writes, with the best test result of 5,324MB/s.

When it comes to random performance the drive is rated as up to 1,000,000 IOPS for reads and up to 720,000 IOPS for writes but as you can see from the Peak Performance results, the best we saw from the drive in the CDM 7 benchmark was 233,898 IOPS for reads and 324,958 IOPS for writes.

We also used CrystalDiskMark 7 to test the random performance of the drive at lower queue depths (QD1 – QD8) where most of the everyday workloads occur) using 1 to 4 threads. The WD Black SN850’s read performance climbs smoothly throughout the tested queue depths and threads with a peak performance figure of 347,914 IOPS (1,425MB/s) at QD8.

In the write tests, the best performance came from the three threaded test run which reached 368,492 IOPS (1,509MB/s) at QD8.

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