What does partition alignment mean?

Partition alignment is the proper alignment of partitions to the reasonable boundaries available in a data storage device, such as, hard disk, solid state drive, or RAID volume, which ensures ideal performance during data acess. In comparison, performance is improved by 10-30%or more. Usually, the SSDs are 4096 or 8192 bytes, and avanced formatted hard disks are 4096 bytes.

And the Windows installer know how to handle this properly, and it will do partition alignment when you install Windows on SSD or get a computer with SSD on it. But if you replace HDD with SSD, it may not do for you, thus the partition is not aligned. You may find SSD boot low after cloning or restoring

In general, a typical mechanical hard drive starts its first partition after 63 empty blocks while a solide state drive start after 64 empty blocks. Thus, if the disk is not aligned, the physical sectors and cluster will be shifted, to be specific, you have to read two physical 4K sectors for a file in one cluster. 


A cluster is the smallest logical amount of disk space that can be allocated to hold a file. One cluster can only hold content of one file no matter how small the file is.

When should I use partition alignment?

After learning the basic info of partition alignment, you may know it is good for disk performance. At the same time, incorrect aligned will slow down the performance as well. Here we summarize some situation you should use it:

  • Migrate system, disk, partition under the old version of Windows, including Windows XP, Windows Server 2003, Windows 2000, etc. They do not include this feature. 
  • SSD slow boot after cloning or restoring. In this case, the Windows Installed does not align partition for you, and you need to do it manually.

How do I know if my partition is aligned?

If you find your SSD boot slow after cloning or restoring, you can check if it's aligned in the System Information. Below are the steps: 

Step 1. Press Win + R to open the Run window, input msinfo32 and hite OK.

Step 2. Go to Components > Storage > Disks, find your SSD and the Partition Starting Offset. 

Check SSD Alignment

Step 3. Then, divide the figure in Partition Starting Offset by 4096. If it is evenly divisble by 4096, the partition is correctly aligned. If you get a fractional number, then SSD partition is misaligned. 

If your SSD is not aligned correctly, you can choose to align it during the clone or restore process. It's an auxiliary feature attached to clone feature and restore feature and the software you use will  align sectors for the partition or hard disk automaticaly if you tick the aligned sector option. And I'll introduce you the steps in detail. 

How to perform SSD Alignement during Clone or Restore process

To perform SSD Alignment during Clone or Restore process, you need all-in-one software that supports both of them. AOMEI Backupper Professional is a good choice. It works well in cloning partition or hard drive to SSD or restore image to SSD and can ensure the disk is bootable after cloning or restoring. 

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(PS: This software only applies to Windows 11/8/10/8/7/XP/Vista. For server users, try AOMEI Backupper Server. )

Situation 1: Align sector while performing clone

The SSD Alignment is applicable to Partittion Clone, System Clone and Disk Clone, you can select one of them, depending the items you want to backup and the space of target disk. Here take Partition Clone as an example.

Step 1. Launch this software, choose Partition Clone under the Clone tab.

Partition Clone

Step 2. Choose a source partition, E partition for example. Click Next to continue.

Select Source Partition

Step 3. Choose a destination partition ( here is Disk1). Click Next to continue.

Select Destination

Step 4. Tick the SSD Alignment option and then click Start Clone, it will align partition during the cloning process.

Ssd Alignment

Situation 2: Align sector while performing restore

Step 1. Click Restore tab after launching this software, and then Select Task to see the Backup list.

Select Task

Step 2. Choose the backup image and items you want to restore. Then, click Next in each step.

Step 3. In the Operation Summary window, tick "SSD Alignment" and click 'Start Restore". It will perform 4k alignment automatically in this task.

Ssd Alignment


You can easily fix SSD slow boot after cloning or restoring with the help of complete backup and restore or clone software - AOMEI Backupper Professional. Its SSD Alignment uses 4k alignments, which can align partition for you automatically. 

Also, you can enjoy more advanced features, such as, Edit Partitions, it allows you to make full use of disk space on the destination disk. If you are migrating MBR HDD  to GPT SSD, you still can convert the destination disk from GPT to MBR without losing data. Download it to have a try ! or learn more in the edition comparison page.