Tips for expanding *.vmdk disk in VmWare

There is good utility vmware-vdiskmanager.exe in VmWare Server for Windows, which can expand your virtual machine disk. But as disk size parameter you need set not delta disk size but final desired disk size. See my examples:

I need add +10Gb extra, and try to execute following command:
#vmware-vdiskmanager -x 10Gb WinXP2.vmdk
Failed to expand the disk 'WinXP2.vmdk': One of the parameters supplied is invalid (1).


Another atempt was more successful:
#vmware-vdiskmanager -x 30Gb WinXP2.vmdk
The old geometry C/H/S of the disk is: 16383/16/63
The new geometry C/H/S of the disk is: 16383/16/63
Disk expansion completed successfully.