How to check allocation unit size in Windows

lee_gomez

How do I know my allocation unit size? I have a 120 GB hard drive, and I want to format it. I have been told that I need to know my allocation unit size, but I don't know how to find out. Can someone please help?

If you are using Windows, you can find your allocation unit size by going to "My Computer", right-clicking on the hard drive you want to format, and selecting "Properties". Under the "General" tab, it will say "Allocation Unit Size".

rudi_hirth

Windows calculates the allocation unit size based on the size of the volume and the file system. NTFS uses a smaller allocation unit size for volumes less than 4 GB and uses a larger allocation unit size above 4 GB.

The default allocation is 4096 bytes, but the NTFS file system can be configured to use a smaller or larger allocation unit size.

If you want to change your allocation unit size, you can use the Format command. For example, the following command sets the allocation unit size to 512 bytes for the E: drive:

format E: /a:512

For more information about the Format command, see Format a Disk (http://go.microsoft.com/fwlink/?LinkId=214583).

Cathhy112

Each NTFS volume has an allocation unit size, which is the smallest amount of disk space that can be allocated to a file. The allocation unit size is set when the volume is formatted and cannot be changed.

To determine the allocation unit size of an NTFS volume:

Open a command prompt.
Type fsutil fsinfo ntfsinfo drive: and press Enter, where drive is the drive letter of the NTFS volume.
The output from the command will include two lines that say Bytes Per Sector and Bytes Per Cluster. The allocation unit size is equal to the number of bytes per cluster.

For example, if the output from the fsutil command shows that the bytes per cluster is 4096, then the allocation unit size for the volume is 4096 bytes.

You can also view the allocation unit size in the Properties dialog box for the volume. To do this, open File Explorer, right-click the volume, and then click Properties. The allocation unit size is displayed under the General tab.