Crucial MX100 (256GB & 512GB) Review

Random Read/Write Speed

The four corners of SSD performance are as follows: random read, random write, sequential read and sequential write speed. Random accesses are generally small in size, while sequential accesses tend to be larger and thus we have the four Iometer tests we use in all of our reviews.

Our first test writes 4KB in a completely random pattern over an 8GB space of the drive to simulate the sort of random access that you'd see on an OS drive (even this is more stressful than a normal desktop user would see). We perform three concurrent IOs and run the test for 3 minutes. The results reported are in average MB/s over the entire time.

Random read performance remains mostly unchanged. The 512GB MX100 appears to be slightly faster than the M550 while the 256GB version is a few megabytes slower.

Random write performance, on the other hand, is slightly up at the lower queue depths. This is likely due to firmware optimizations as the performance is up regardless of the capacity, although once the queue depth is increased the 256GB version falls behind due to the more limited amount of NAND die.

Sequential Read/Write Speed

To measure sequential performance we run a 1 minute long 128KB sequential test over the entire span of the drive at a queue depth of 1. The results reported are in average MB/s over the entire test length.

Sequential performance is also up by a bit, although the difference isn't dramatic.

AS-SSD Incompressible Sequential Read/Write Performance

The AS-SSD sequential benchmark uses incompressible data for all of its transfers. The result is a pretty big reduction in sequential write speed on SandForce based controllers.