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How to give more hard disk space to a Windows virtual machine

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You’re running out of free space on your virtual machine, and you want to increase the size of the virtual hard disk.


Even if you have an expanding virtual hard disk, it won’t expand above the limit set in virtual hard disk configuration. To allow further expansion, you must increase the size manually.


Warning! We strongly recommend that you check your virtual machine's hard disk for errors and back up your virtual machine before following the steps below.

Note: This article does not apply to Boot Camp virtual machines, where the primary partition size cannot be increased.

To increase virtual hard disk size, do the following:

  1. Start Parallels Desktop, but do not start your virtual machine. Shut it down if it is running.

  2. Right-click on the Parallels Desktop icon in the Dock, then select Control Center (Virtual Machines list in older versions).

  3. Right-click on your virtual machine and choose Configure.

  4. Go to the Hardware tab, open Hard Disk 1, and click Edit.

  5. Choose the size you want for the virtual hard disk, check “Resize file system,” and click Apply.

To make sure the changes were applied successfully, confirm that the size of the virtual hard disk has changed:

  1. Start the virtual machine.
  2. Open the Start menu.
  3. Type “Control Panel,” then hit Return.
  4. Administrative Tools > Computer Management > Disk Management.

The size of the main partition (the partition where the Windows installation is located—it is local disk (C:) by default) should equal the size of the virtual hard disk (Hard Disk 1).

If the Resize File System option is grayed out or you cleared its checkbox, you will see that the size of Hard Disk 1 in the virtual machine’s configuration has changed, but the size of local disk (C:) in Windows has not.

In that case, do the following:

  1. Start the virtual machine.
  2. Open the Start menu.
  3. Type “Control Panel,” then hit Return.
  4. Administrative Tools > Computer Management > Disk Management.

Disk Management reports that you now have an extra partition on the hard drive that’s marked as Unallocated. You can add this Unallocated partition manually to your main disk (C:) partition:

  1. Right-click on the main (C:) partition and select Extend Volume.

  2. Extend Volume Wizard will open. Click Next.

  3. On the Select Disk page, you may choose how much extra space should be added to the main (C:) partition. By default, the whole Unallocated partition will be added. Click Next,

  4. Click Finish on the next page, and the Unallocated partition will be added to the (C:) partition.

  5. In Start > Computer, you’ll see that local disk (C:) has been resized.


  • If you are unable to expand your virtual hard disk, see KB 121313.
  • If you have trouble resizing your hard disk, see KB 8004.
  • For the list of supported file systems, see KB 113840.

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