This option extends the size of a disk allocated to a virtual machine after the virtual machine has been created.

-X --extendvirtualdisk newSize[kK|mM|gG]

You must power off the virtual machine that uses this disk file before you enter this command. You might have to update the file system on the disk so the guest operating system can recognize and use the new size of the disk and take advantage of the extra space.

You specify the newSize parameter in kilobytes, megabytes, or gigabytes by adding a k (kilobytes), m (megabytes), or g (gigabytes) suffix. The unit type is not case sensitive. vmkfstools interprets either k or K to mean kilobytes. If you don’t specify a unit type, vmkfstools defaults to kilobytes.

The newSize parameter defines the entire new size, not just the increment you add to the disk.

For example, to extend a 4g virtual disk by 1g, enter: vmkfstools -X 5g disk name.dsk


Do not extend the base disk of a virtual machine that has snapshots associated with it. If you do, you can no longer commit the snapshot or revert the base disk to its original size.