4K alignment refers to a hard disk that is formatted in line with the "4K sector" definition and is written to the data according to the rules of "4K sector".

With the development of the era, the capacity of hard disk is expanding, so that 512 bytes of each sector defined before are no longer reasonable, so the 512 byte of each sector is changed to 4096 bytes of each sector, that is, the "4K sector" that is often said. With NTFS becoming standard hard disk file system, the default allocation unit size file system (cluster) is 4096 bytes, in order to make the cluster and sector should be relative, even using the physical hard disk partition and computer logic partition alignment, ensure the hard disk read and write efficiency, so there is the concept of "4K alignment".

In the era of solid-state hard disk, if 4K is not aligned, it will not only greatly reduce the speed of data writing and reading, but also increase the number of unnecessary writes and affect the life of SSDs. So when using a solid state hard disk, it must be 4K aligned to make the solid hard disk fly.

In daily life, we can use the win7, 8 or win10 system built-in disk management tools to perform formatting to achieve 4K alignment. You can also use some professional hard disk partition software to achieve 4K alignment, such as DiskGenius (hard disk partition), partition assistant, and so on.

At the same time, you can use AS SSD Benchmark to see whether 4K is aligned on solid state hard disk. As shown in the red box above, if the word "OK" is behind the figure 10242048, SSD is 4K aligned. If there is no word "OK", it shows that 4K is not aligned.

If the number in front of "OK" is very large and is not a number of 10242048, it shows that the hard disk divides the hidden partition when the operating system is installed. When the win7 system is installed, the hidden partition of the 100M will be generated automatically. When the win8 system is installed, the hidden partition of the 350M will be generated automatically. As long as you don't keep the C disk before the hidden partition, then "OK" will be displayed in front of 10242048 figures such as. If you keep it, the number in front of "OK" will be big.