Crucial MX500 4 TB in the test: Double TLC-NAND for the 25th company anniversary

Crucial is expanding the popular MX500 SSD series in 2.5-inch format with SATA upwards. The new 4 TB model continues to use TLC-NAND and has to prove in the test whether it is a worthy addition to the SSD series with SATA connection. At around 350 euros, the price is comparatively low.

Table of contents

1. 1 Double TLC-NAND for the 25th Company anniversary
   1. The MX500 is a best seller
   2. The new addition with 4 TB
   3. The DRAM is now being saved
2. 2 benchmarks, cache analysis and temperatures
   1. Test system and test methodology
   2. Cache analysis (SLC mode)
   3. Copy processes in Explorer
   4. Performance consistency in PCMark 10
   5. CrystalDiskMark
   6. Temperatures over time
3. 3 Conclusion

The MX500 is a best seller

The Crucial MX500 SSD series (test) came onto the market at the end of 2017. With more performance than its predecessor, good equipment and a longer warranty, the MX500 turned out to be the best SSD in the MX series since the MX100 (test) and did not show any major weaknesses. There was also a very low price. The editors' prognosis that the MX500 will sell very well was therefore not too daring and has been fulfilled.

The following years and until today MX500 models have been found in the top 10 most popular data carriers in the price comparison. The MX500 is also a permanent guest when it comes to recommendations from the editors and the community, unless it is supposed to be a faster NVMe SSD.

MX500 with large sales at Mindfactory

The 500 GB model was more at the retailer Mindfactory sold more than 50,000 times – no SSD from Samsung's popular Evo series has managed that, although numbers for the now discontinued 850 Evo (test) are missing here.

While Samsung presented the 860 Evo (test) and the 870 Evo (test) as successors, the Crucial MX500 also plays its age in the sales figures.

The recipe remained almost unchanged

The 2.5-inch version of the MX500 in particular was and is popular, even if the series is also available in the M.2 form factor. Up to now, storage capacities of 250 GB, 500 GB, 1 TB and 2 TB have been offered in the classic design. The main components were initially the SM2258 controller from Silicon Motion and 3D-TLC-NAND from the 64-layer generation from the parent company Micron.

Later the series received a “fresh cell cure”: The new edition with the firmware M3CR033 comes up with the younger SM2259 controller and 96-layer NAND with more storage capacity per chip . At least in a direct comparison of the 1 TB models, the performance remains almost the same and the MX500 is still a recommendation for price-conscious SATA buyers.

The new entry with 4 TB

In parallel to the 25th anniversary of the Micron brand, Crucial is expanding the MX500 series with a 2.5-inch model with 4 TB of storage space. As with the new edition of the 1 TB model, the SM2259 controller is used. Just like this one, four NAND packages are built in, but each has 16 dies of 512 Gbit each, which means four times the storage capacity of 1 TB per package and 4 TB in total. Crucial has not yet revealed which generation TLC-NAND it is.

Crucial MX500 SSD with 4 TB

Crucial MX500 .jpg”

The configuration is surprising, because according to the public specifications (PDF) for the SM2259, the 4-channel controller from Silicon Motion actually only supports a maximum of 32 chips (8 CE per channel). However, in this case there are 64, i.e. twice as many chips (dies). When asked about this, Crucial explained that all 64 dies can still be addressed by the controller using “4-Way Interleaving Mode”. The performance should not be affected by this and should be on the level of the 2 TB model.

If Micron were to use its own QLC-NAND with 1,024 Gbit instead of TLC-NAND with 512 Gbit, the limit of 32 chips could also be kept. However, QLC-NAND is slower and less durable.

The decision to keep TLC-NAND is initially laudable, but it has to be shown how efficient the controller is with the 64 memory chips can really manage. The editors are not aware of any other SSD with an SM2259 controller and 4 TB storage space.

The DRAM is now saved

The basic recipe consisting of the SMI controller and 3D-TLC-NAND is therefore retained. However, there is a clear step backwards with the DRAM cache: only a 512 MB DDR3 component is available. That's only an eighth of what would actually be standard with 4 TB SSDs. Because in general the rule of 1 GB DRAM per 1 TB of storage space applies, which would mean 4 GB. For reasons of cost, however, less and less DRAM cache is being used or even left out completely.

Crucial admits that this results in a loss of performance for certain workloads, and indeed the decision was felled for cost reasons. However, for most desktop applications, the difference is unlikely to be noticeable.

Together with the controller manufacturer Silicon Motion, Crucial has also worked on the efficiency of the Flash Translation Layer, which is responsible for converting logical into physical addresses for the data. The process, also known as “mapping”, should now work more efficiently and accordingly require less space. Instead of adapting the size of the DRAM to the amount of NAND flash as before, a DRAM cache with 512 MB can now be used for all storage capacities, according to Crucial. It remains to be seen whether this is an indication of further new editions of the MX500 with less than 4 TB.

With NVMe SSDs, 64 MB DRAM is often enough

The following tests will show whether the shrunk cache affects performance. However, this is not to be expected in everyday use. NVMe SSDs without their own DRAM cache have shown that even a few MB of system memory reserved by “Host Memory Buffer” (HMB) are sufficient as a DRAM replacement to prevent a drop in performance. Samsung's 980 (without Pro), for example, only uses 64 MB of system RAM as HMB and therefore shows no weaknesses. SATA-SSDs do not have the NVMe function HMB, so at least a small, dedicated DRAM chip must be installed.

Are neither a (small) dedicated DRAM Cache still HMB support available, there is a risk of system failures, as they had shown with the Toshiba TR200.

On the next page: benchmarks, cache analysis and temperatures