:Resolve the error volume cannot be extended due to cluster limit

Problem description

In Windows, you receive the following error message when you try to extend a partition formatted with the New Technology File System (NTFS) file system: "The volume cannot be extended because the number of clusters will exceed the maximum number of clusters supported by the file system".

Cause

This error occurs when the target size of the partition exceeds the maximum volume size supported by the NTFS file system for the current allocation unit size. Windows blocks the operation to prevent data corruption or file system incompatibility.

For a detailed explanation, refer to the official Microsoft documentation.

Solutions

The allocation unit size is determined when a partition is formatted and cannot be changed on an existing partition.

• To extend a volume to a size from 16 TiB up to 32 TiB (inclusive), the allocation unit size must be 8 KB (8,192 bytes).

• To extend a volume to a size from 32 TiB up to 64 TiB (inclusive), the allocation unit size must be 16 KB (16,384 bytes).

1. Check the Allocation unit size of the disk that you want to extend.

   Log on to the instance, open the powershell command-line interface, and run the following command to check the Allocation unit size. The following example shows how to check drive D:

   In the output, the Allocation unit size is labeled as Bytes per cluster or Bytes per cluster.

   fsutil fsinfo ntfsinfo D:

2. Choose a solution based on your requirements.

   Create a new disk and copy data

   1. Create a new empty data disk with the target capacity on the current instance.

   2. Select the correct allocation unit size when you initialize the data disk.

   3. Copy the data from the original disk to the new disk.

   4. Restart any applications or services that use the disk and verify that they are running correctly.

   5. After confirming that everything is running correctly, detach the original data disk then release it. For details, see Uninstall a data disk and Release a disk.

   Use the extended capacity for a new partition

   1. In the Disk Management dialog box, choose Action > Rescan Disks from the menu bar to view the unallocated disk capacity.

   2. Right-click the unallocated space and select New Simple Volume.

   3. Follow the instructions in the New Simple Volume Wizard and accept the default settings.