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    Senior Program Developer

Related knowledge about 4K alignment. And effective methods about how to optimize SSD performance with 4K alignment.

From Windows 98 to Windows XP, HDD leads the world. For the limited size HDD, the size of the default sector is 512 Bytes. However, with the development of capacity of HDD and in order to improve the HDD performance, the 512 Bytes is not so reasonable. And now it has change to 4096 Bytes per sector which is also called “4K sector”.

What is 4K Alignment?

4K alignment means to make cluster correspond with sector (align physical disk partition with computer logical paritition) to ensure the reading and writing speed of the hard disk.

Advantages of 4K Alignment?

Starting from Windows NT, “NTFS” has become the main file system in Windows. However, the boot sector of NTFS takes up a track (63 sectors, about 512 Byte * 63 = 31.5KB) in hard disk (The disk we mentioned here refers to the traditional hard disk). In other words, the real partitions which is used to save data is behind the 63 sectors.
For traditional HDD, 4K alignment does not mean so much in traditional hard disk. But it get totally different in SSD. If 4K sector is misaligned in SSD, it will lead bad performance of SSD – reduce reading and writing speed and even shorten the life of SSD. The target we replace HDD with SSD is to improve the performance of our computer. And the most attractive advantages of SSD is its higher reading/writing speed. But if 4K is misaligned in SSDthe performance of SSD will almost be the  same  with HDD. We can make comparison from the following test.
Before 4K alignment:

AS SSD Benchmark will show “Bad” if 4K misaligned.

before 4K alignment
After 4K alignment:

AS SSD Benchmark will show “OK” if 4K is aligned.

After 4k alignment
From the test, we can see the impact that 4K alignment brings. It is necessary to make the 4K alignment when you want to replace HDD with SSD. Even you just make the SSD to be the storage device, it is also important to modify it to “4K alignment”.

Optimize SSD Performance with 4K Alignment

After purchasing a new SSD, you can use the built-in tool in Windows 7. The SSD will be 4K aligned after formatted by default.
But if you want to keep the original system in HDD when you want to replace it with SSD, it is recommended to choose the free professional software – Renee Becca to migrate system to SSD.
  • Entirely Free!
  • Align 4K automatically when migrating system.
  • Boot with the new SSD immediately after migration.
  • Whole process just take 4 simple steps.
  • Compatible with Windows 10 / 8.1 / 8/7 / XP / Vista.
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