There are more than 66,000 SSD models on JD.com, which is much more complicated to choose than a CPU or graphics card. Buy the classic model worried about encountering the manufacturer to change the flash memory, buy the newly launched model and afraid of when the mouse overturned in the middle. Storage geeks bought their first SSD in 2010, and today I will share with you the classification and purchase of SSDs.
Now SATA SSDs have no price/performance advantage, unless you don't have an M.2 interface on your computer to consider it. The parameters of NVMe SSD mainly include PCIe version, number of channels, and whether there is DRAM cache.
The PCIe version determines the ceiling height for sequential read and write speeds of the SSD: PCIe 3.0 reads up to 3500MB/s and PCIe 4.0 reads up to 7400MB/s. The system disk does not simply copy data like the mobile hard disk, and there is not much opportunity to use the full read and write bandwidth in actual use, so it has four channels and eight channels. For example, the armored man RC20 recently tested by storage geek belongs to the four-channel NVMe SSD of PCIe 3.0 interface, which is suitable for players who pursue cost performance rather than extreme performance.
The "channel" here refers to the number of flash lanes that the SSD master can manage, which can be roughly understood as the division of four lanes and eight lanes on the highway. PCs only serve a single user, we drive on the highway without congestion, and the four lanes and eight lanes do not affect the time it takes us to reach our destination, so the four-lane SSD is not necessarily slower than the eight-lane.
Finally, there is the DRAM cache, the rectangular chip closest to the M.2 interface on the RC20 is the DRAM cache chip, and not all SSDs will have this chip. What is stored in the DRAM cache is not the content of the file read and written directly by the computer, but the "metadata" called the FTL flash mapping table, which is only accessed and used by the SSD master (the square with kioxia chip in the figure below).
For each data read and write operation of the SSD, it is necessary to first look up the FTL flash mapping table to find the mapping relationship between the LBA logical address and the PBA physical address. In the case of an SSD without DRAM cache, this FTL table is stored in flash memory, and the read and write speed of NAND flash memory is far less than that of DRAM memory. This is why storage geeks recommend that you try to choose an SSD with DRAM cache.
The figure below is a comparison of the AS SSD Benchmark speed measurement of the Armored Man RC20 1TB and the Western SN550 1TB. Storage geeks choose them for comparison because they have a good relationship and are close to the price. Kikuya is renamed from Toshiba Memory, and Nishimo's flash memory is all derived from a Japanese factory that is a joint venture with Kazuya. The flash memory of the RC20 and SN550 is the same origin, only the master and DRAM caches are different. In order to pull away the positioning of RC20 and RD20, the interface frequency of flash memory is limited to 666MT/s in RC20, and the sequential read and write is slightly lower than that of SN550, but the random read performance is stronger with the help of DRAM cache.
SSDs without DRAM cache can share a part of the computer host memory through HMB for cache use, but Windows limits can only share up to 64MB, corresponding to 64GB of NAND flash space, and the limitations in actual use are more obvious. The 3DMark storage test demonstrated the impact of the SSD on the gaming experience, with the Armored Man RC20 1TB scoring 2494 points:
The Western SN550 1TB has higher average access latency and lower storage bandwidth, with a total score of 2355:
Procyon productivity performance testing tools include performance testing for office applications, photo editing, and video editing. The test items include the common Office and Adobe family buckets, which are very representative. The following storage geek uses it to compare the impact of the ARMORED RC20 with DRAM cache and the Western Digital SN550 without DRAM cache on productivity application performance.
Procyon Office Productivity Score: Armored Man RC20 6944, Western Digital SN550 6933.
Procyon Photo Editing Benchmark Score, Armored Man RC20 8882, Western Digital SN550 8767.
Procyon video editing score: ArmorEd Man RC20 6608, Western Digital SN550 6581 points.
Although the 2400MB/s sequential read speed of the Western Digital SN550 is higher than the 2100MB/s of the Armored Man RC20, due to the impact of DRAM caching, both the game performance and the productivity performance are stronger than the Armor Man RC20. This also continues the result of the duel between RC10 and SN550: western number order reading is faster, and armored man is actually stronger.
Finally, the storage geek's view is that the DRAM cache will not suffer. Now the mainstream NVMe SSD with DRAM cache options are not much, to people who do not understand the computer can recommend parameters good-looking but no DRAM cache, if it is their own use, it is still necessary to be practical king.