Results: Sequential Performance
Fantastic sequential read and write performance is a trademark of modern SSDs. To measure it, we use incompressible data over a 16 GB LBA space, and then test at queue depths from one to 16. We're reporting these numbers in binary (where 1 KB equals 1024) instead of decimal numbers (where 1 KB is 1000 bytes). When necessary, we also limit the scale of the chart to enhance readability.
128 KB Sequential Read
As we've seen from some of our recent SSD reviews, performance at low queue depths starts slow, and scales up as outstanding commands pile up. I speculate that our 128 KB sequential workload isn't intense enough to fully saturate Adata's SP920s. Perhaps its an artifact of larger page sizes (16 KB in this case).
All four drives are more or less equal in this test, peaking at almost 540 MB/s at a queue depth of four. I'm using 128 KB chunks of data, whereas a test utility like AS SSD is going to use somewhere in the range of 1 to 4 MB.
128 KB Sequential Write
128/256 GB Adata SP920
I'll start by write testing the two smaller SP920s, and comparing them to the older Crucial M500 equivalents. Why am I dipping back to the 120 and 240 GB M500s? Unfortunately, Crucial didn't send along its 128 and 256 GB models for review, which benefit from twice as many dies as Adata's SSDs. So instead of making this face-off about interleaving, it's instead a measure of firmware and controller performance. Even with the same NAND, we realize a notable speed-up from the two Adata offerings.
The 128 GB Adata SP920 achieves 177 MB/s, which is quite a bit faster than the 120 GB M500's result in the mid-130 MB/s range. The 256 GB model's jump is even more impressive; it registers an extra 100 MB/s. That's awesome, and very close to Adata's official specification. However, the 256 GB M550 is supposed to achieve 500 MB/s. Those extra dies prove useful in a test like this one.
There is a tradeoff here.
512/1024 GB Adata SP920
The larger models fare far more predictably, and we see total parity between the bigger drives with the same number of dies. Performance that falls just shy of 500 MB/s is a result of Micron's flash and firmware. It's about 100 MB/s more than the M500 delivers, though the real fruits of this platform are found elsewhere.
Here's a breakdown of the maximum observed 128 KB sequential read and write performance with Iometer:
The SP920s fall a few megabytes per second short in our benchmark, which are enough to put Adata's largest two models behind the Crucial M550s at the top. In any case, that small amount of difference is imperceptible.
