SanDisk Z400s SSD Review

Mixed Workload And Steady State

80 Percent Sequential Mixed Workload

Our mixed workload testing is described in detail here, and our steady state tests are described here.

In this test, we use sequential data mixed at 80 percent reads and 20 percent writes. This is right around the ratio characteristic of most home users. The drives are not in steady state, but they are conditioned prior to benchmarking. Mixing in those writes pulls the Z400s' performance down from what we saw when we were testing 100 percent reads on the previous page.

80 Percent Random Mixed Workload

The Z400s' random reads and writes fall below current standards. But when they're combined in a mixed workload, performance plummets. Still, the outcome we observe is better than what you'll get from a hard drive.

We can't ignoring pricing on this one. Just because an SSD is faster than a mechanical disk doesn't mean there isn't an even faster SSD selling in the same range.

Sequential Steady State

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We often talk about the two steady state tests being specialty workloads that most users never encounter. Without a DRAM buffer, it's easier to beat the drive down to these lower-performing states, as the page table map is updating with each write to the drive. Those are random operations, by the way, which wear flash faster than sequential transfers.

Random Write Steady State

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In steady state, the Z400s has difficulty writing a lot of data quickly. The Adata SP500 hugs the same low performance levels, but also has very pointed peaks where the buffer and over-provisioned flash area increase performance. I'm surprised SanDisk didn't also launch its Z400s with over-provisioned space to help deal with background activity.