The performance of an SSD depends on several factors as we have been explaining to you in the many articles that we have been publishing about the main internal storage format of a PC. Today we bring it up as a result of the controversy caused by the reduction in performance of the latest version of the WD Blue SN550, one of the most interesting solid state drives in the consumer market as we could see in this analysis.
The Chinese technology web portal Expreview analyzed a new version of this WD Blue SN550 finding a big performance decrease (-50%) compared to previous versions when the cache was exhausted. The issue has been confirmed by other means and has sparked controversy. Should WD have previously reported the changes before marketing the new units?
Understanding the performance of an SSD
In addition to the NAND flash memory that is used for data storage and the extra cells for when those fail, almost all solid state drives include a additional memory for data cache. It varies in capacity and performance depending on the model, but it is a very important component especially when handling the most used data writing.
The WD Blue SN550 uses 96-layer SanDisk TLC 3D NAND memories and also features SLC memory for cache (12 GB). This type of memory is much faster than general NAND flash and allows to increase the performance of the unit, but as in any other SSD or electronic product that uses them (such as hard drives or CPUs) it only maintains its performance when it has the capacity to do so. . When it runs out, the aid runs out until it refills.
The management of this cache memory is carried out by the installed driver and is internal, automatic and efficient. Always depending on the amount installed, a typical user does not usually notice loss of performance in common tasks. But it can be noticed in more advanced tasks or those that require moving a greater amount of data and that ends up depleting the cache, 12 Gbytes in this case.
The controversy arises because WD has replaced the flash memory, the firmware and the amount of cache. The WD Blue SN550 is still fantastic in terms of performance / price as a mid-range PCIe SSD and still offers the original values in sequential reads and writes (2,400 / 1,950 Mbytes per second), but when the cache is depleted it loses a lot of performance.
Western Digital has recognized the issue and promises greater transparency in the future: “In June 2021, we replaced the NAND on the WD Blue SN550 NVMe SSD and updated the firmware… At that time, we updated the product data sheet. For greater transparency in the future, if we make a change to an existing internal SSD, we promise to introduce a new model number whenever related published specifications are affected. “.
WD has not reported the reasons for the hardware changes, but they may be related to the global semiconductor shortage caused by the COVID pandemic. It affects the entire planet and all industrial sectors and we fear that it will not normalize until well into 2022.