Both the WD SN550 and the Crucial P2 , both with 1 TB, have become the target of many users, on the one hand is its relationship between the capacity it has and its price and on the other the fact that they are not SATA but NVMe. But how do these two storage drives compare to each other and to the rest of NVMe SSDs?
There is no doubt that NVMe SSDs are going to become an indispensable piece in every PC, especially those that are used to play games. And it is that little by little and at a constant rate more and more games are recommending installing them in a storage of this type. All this without forgetting the advantages that in general they provide compared to a conventional hard disk, which are not only reduced to a higher transfer speed, but also a shorter search time and the fact that they do not use parts mobiles.
However, today an NVMe SSD is hardware that is expensive at the moment, especially in the capacity / price ratio, where HDDs have an advantage and will maintain it for the next few years. We must emphasize that the pros that an NVMe SSD offers to the software can never be equaled by a hard disk and these are not only reduced to lower loading times and installation speed.
That is why we have decided to make a comparison of two models of NVMe SSD under PCI Express interface with a capacity of 1 TB , with very similar characteristics and a good performance ratio with the price of each one. We are talking about the Crucial P2 and the WD Blue 550 both in the same category, that of the M.2 with 2280 form factor.
Crucial P2 1TB Features
The Crucial P2 is an NVMe SSD that we could call low-end, this is because despite being compatible with a PCIe Gen 3 interface it does not saturate the data bus, since its maximum transfer speed is 2.4 GB / s read and 1.8 GB / s write , in both cases this figure is achieved by sequentially accessing the data from the SSD. The reason for the lower transfer speed, and also its price, is because it uses RAM memory as a cache between the flash controller and the PCI Express port.
The Crucial P2 makes use of the Host Memory Buffer which is based on the fact that it can use the RAM of the system by accessing it through the PCIe interface and an integrated DMA unit and therefore we are facing a DRAM-Less model . In passing we clarify that it is not compatible with PlayStation 5, not because it does not meet the minimum bandwidths of the specification, but because it does not have DRAM memory integrated in the M.2 unit.
As a last point, the Crucial P2 does not support protection for loss of power or PLP , which makes it not recommended for a server type system that has to work 24 hours a day, 7 days a week and in the which it is recommended that the devices have measures against voltage dips. So discard it out of the box for a data center or server.
1TB WD Blue SN550 Features
The WD Blue SN550 has specifications very similar to the Crucial P2, such as a sequential read and write speed of 2.4 GB / s and 1.75 GB / s respectively . So at first glance it may seem like a somewhat slower unit in that regard, but later on you will be surprised. In any case, we must clarify that in the applications at the time of being used what abounds are the random accesses to the SSD and not those that are made in series or sequential.
The reasons for the lower bandwidth or transfer speed in the WD Blue SN550 are the same as in the Crucial P2, since we are also facing a so-called DRAM-Less SSD . So despite using a PCI Express interface, the speeds of standard NVMe SSDs are not achieved, although they are faster, they are a better option than M.2 SATA SSDs, which are affected by the bottleneck of said interface.
The biggest limitation, which has brought controversy, is the capacity of the SLC Cache of the WD 550, which is very small and causes the transfer of large files to be affected badly and therefore this ends up cutting the performance of the WD Blue SN550. Although if we are fair we have to say that we do not know if the Corsair P2 has the same handicap, so it is best to focus on the differences in performance between both solid state drives.
WD SN550 and Crucial P2 compared
We come to the part that interests us, which is how the Crucial P2 compares with the WD SN550 in terms of performance and that is why we have decided to take some results from comparative benchmarks that have been ordered so that the information is easier to find. interpret. It should be clarified that the performance tests have been separated into two different groups and, on the one hand, we have taken those that speak of random and sequential accesses.
The explanation? Every controller of a solid state drive is always ready to access the next address it is currently at, which allows it to read or write the information serially, that is, in sequence. The point is that if the CPU makes a request to another address of the non-volatile RAM, which is the NVMe, then a jump has to be made to a different part of the SSD storage and in that period no data is transmitted. For this reason, manufacturers do not usually talk about speeds in random mode.
The other point to keep in mind is the writing of data to NVMe memory. Most of the time the applications do not work on the massive storage of the system, but they do it in the RAM where previously the data that is necessary in the hard disk or the solid unit is accessed and is copied in the system memory. So they will be modified by the CPU and other processing units in RAM. That is why many times when you do not save a file it is lost, due to the fact that you do not tell the program to dump the data to persistent memory.
And why are we commenting on this? Well, for the simple fact that the Crucial P2 1 TB seems to have a very low write performance to the SSD when we write large volumes of information, which makes it completely lose this comparison.
