Allocation unit, also known as cluster, is the smallest unit of file management in Microsoft operating system. A cluster includes a number of sectors, and traditionally the sector size is 512 bytes for HDD. Usually the size of a cluster can be customized when you perform “Format” in Disk Management.
Since the cluster size can be customized, different hard drives or partitions have different utilization ratios. Depending on the file size, a single file occupies at least one cluster, but one cluster cannot be shared by two or more files. Thus, in most cases each file takes up a larger disk space than it actually needs, which is a waste of disk space in a certain degree.
Microsoft keeps 4096 bytes as the default of allocation unit size in Windows. But sometimes you need to make your own decision. Assuming you have a file which will occupy 4097 bytes to store but the cluster size of the target partition is 4096 bytes. Obviously this file will occupy two clusters, i.e. 8192 bytes. However, if you change the allocation unit size to 512 bytes, the file will occupy 9 clusters, i.e. 4608 bytes, much smaller than 8192 bytes. This example shows that a smaller cluster size saves more disk space. Nevertheless, each coin has two sides. A smaller cluster size will lead to low working efficiency for the hard disk will deal with more clusters.
So we can draw a conclusion that if you have lots of small files, then it’s good to keep the allocation size small so your hard drive space won’t be wasted. But for large files like videos, a larger cluster size is necessary.
It is also advisable to set different cluster sizes for different partitions and classify your files to store. In this way you can both make full use of your hard drive, and improve the efficiency of hard disk.
Now you may wonder: how do I know the specific allocation unit size of a partition? In windows operating system, we can use the command “Chkdsk” to check the cluster size of a partition. For example, to know the cluster size of C drive, we can execute “Start > run > cmd > C: > chkdsk” and then wait for the analysis result.
If you think the allocation unit in a specific partition is not large enough, then you may head to find a solution to enlarging allocation unit. Here we offer two methods for you.
When it comes to changing cluster size in Windows 7, users may firstly think of using Disk Management. But you have to admit this is a bad way, for you can only carry out this operation when you are about to format a partition. What if you have stored a sea of important data in that partition? Move these data to another location, change the cluster size, and then copy these data back? Definitely NOT!
Therefore, we have to keep on going, and find a feasible method to enlarge allocation unit size without losing data. Luckily, there is a lot of third-party software for us to choose, and MiniTool Partition Wizard Professional is among the most reliable programs.
MiniTool Partition Wizard Pro enables Windows users to change cluster size without data loss or backup. It has a clear interface and is user-friendly to operate. You can finish this change by several clicks.
Step 1. After launching this program, you will see all your disks/partitions listed in the middle panel. Select the partition you are going to change cluster size and right click on it, and then a great many of features emerge. Now you can choose “Change Cluster Size“.
Step 2. In this part, you can choose the cluster size in the drop-down list. After that ,click “Yes” to go on. Finally, press the “Apply” button to execute.
Pretty easy, right? This partition tool can not only deal with local hard drives, but also change cluster size of external USB flash drive. Now download MiniTool Partition Wizard Professional to customize the allocation unit of your hard drive.