Crucial MX200 (250GB, 500GB & 1TB) SSD Review

Final Words

By having two separate BX and MX lineups, it's clear that Crucial is trying to position the MX200 in the higher-end segment and aim the drive towards enthusiast and professional users. On paper that works well because the MX200 does deliver considerably higher maximum performance than the BX100 and the feature set is more professional-oriented with hardware encryption support, but unfortunately the MX200 doesn't fulfill its promises in real world based IO trace testing. In fact, it turns out that the BX100 performs better in typical low queue depth client workloads.

That actually speaks of an industry wide problem. Most manufacturers only publish performance figures at high queue depths (typically 32, i.e. the max of AHCI), but as our IO traces show, only a fraction of real world client IOs happen at such a high queue depth. Even very intensive client IO workloads rarely go above QD2, so it's totally unrealistic to use QD32 figures as the basis of marketing and product positioning. Of course everyone likes big numbers, especially the marketing teams, but the truth is that focusing solely on those can potentially result in erroneous product positioning like in Crucial's case. I think the industry as a whole should try to move more towards low queue depth optimization because that yields better user performance and at the end of the day it's the user experience that matters, not the number of IOs the drive can theoretically process. 

Another thing I'm not very satisfied with is the Dynamic Write Acceleration. I don't think an SLC cache is very useful in an MLC based drive because the performance benefits are marginal, at least with SATA 6Gbps. PCIe and NVMe open the door for potentially higher peak performance, but even then I think the design of DWA is inherently flawed. You don't really need more than a few gigabytes of SLC cache in a client drive because client workloads are bursty by nature, meaning that running as much NAND as possible in SLC NAND doesn't provide any substantial performance gain. In fact, DWA actually works against itself in more sustained workloads because everything is written to SLC (basically all empty space is in SLC mode in the 250GB MX200), so if you write more than the SLC cache can incorporate at the time the drive needs to transfer data from SLC to MLC in-flight, which has a larger negative impact on performance compared to just writing straight to MLC NAND that competing SLC cache designs do. As we saw in our tests, filling the 250GB MX200 with data results in performance decrease that is by far larger than we've encountered on other drives. 

The pricing is obviously higher than BX100, but compared to other high-end SATA drives the MX200 is pretty reasonably priced. That said, it still doesn't provide enough value for the money because the only advantage the MX200 has over the BX100 is hardware encryption, but if that's something you need/want the 850 EVO provides better bang for the buck given that it's cheaper, offers higher performance and you even get a 5-year warranty versus Crucial's three years. 

I think Crucial seriously needs to reconsider its product positioning strategy. If Crucial can't deliver a true high performance drive, then I think it's better to focus all resources on one drive rather than have two overlapping products. I really liked the MX100 because it was such a simplified lineup, whereas the MX200 just adds unnecessary complexity without providing any real value. The BX100 is still a great drive and definitely at the top of my list of value drives, but as it stands today I honestly can't see a scenario where the MX200 would be a justifiable purchase because the performance just isn't anywhere near good enough to justify the higher price tag.