How can you increase a VMware virtual machine’s disk size and expand its partition?

First, expand the virtual disk. In VMware Workstation, ensure the VM is powered off and all snapshots are removed. You can either use the graphical interface by navigating to Edit Virtual Machine Settings > Hard Disk > Utilities > Expand, or use the command line tool such as vmware-vdiskmanager -x vm.vmdk to resize the VMDK file.

In ESXi environments, log in to the ESXi host or vSphere Client, edit the VM settings, and increase the size of the virtual hard disk directly. Save the changes to apply the new disk capacity.

Second, extend the partition inside the guest OS. After increasing the virtual disk size, the added space appears as unallocated storage within the VM. For a Windows VM, open Disk Management, right-click the adjacent partition, and choose Extend Volume to allocate the newly available space. Complete the wizard to finalize the expansion.

Before resizing, always ensure:

The VM is powered off.

All snapshots are deleted.

A backup is available to prevent data loss.

Proper preparation reduces the risk of corruption and ensures a smooth disk expansion process.

Q1: Why can’t I expand the disk when snapshots exist?

VMware blocks disk resizing if active snapshots are present. Remove all snapshots first.

Q2: Why does the guest OS still show the old disk size?

You must extend the partition inside the guest OS after expanding the virtual disk.

Q3: Is a reboot required after resizing?

Sometimes yes, especially if the guest OS does not immediately detect new storage.

Q4: Should I back up before resizing a disk?

Yes, resizing operations carry risk, so a backup is strongly recommended.