When running virtual Windows 2003 systems (e.g. in VMware), it's sometimes necessary to increase the size of the disks to add more storage to your machine. Starting from Windows 2008, you can perform an online increase of NTFS partitions using Storage Manager. In Windows 2003, it's also possible to perform an online extend by using diskpart from the command line.

First, make sure to extend the physical volume (e.g. by increasing the virtual disk size in VMware). Then open a command prompt and run diskpart without parameters.

To extend, you have to select the physical disk and volume. To know what to select, you can view the available disks and volumes.

List and select the physical disk:

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