There are two methods for customizing disks and partitions with Autounattend.xml file: First using the sting and value to display the wizard and customize manually disks and partitions: <DiskConfiguration> <WillShowUI>Always</WillShowUI> </DiskConfiguration>Second do not display the wizard with stings and values already set:Example: <DiskConfiguration> <WillShowUI>OnError</WillShowUI> <Disk wcm:action="add"> <DiskID>0</DiskID> <WillWipeDisk>true</WillWipeDisk> <CreatePartitions> <CreatePartition wcm:action="add"> <Order>1</Order> <Type>Primary</Type> <Size>100</Size> </CreatePartition> <CreatePartition wcm:action="add"> <Order>2</Order> <Size>10000</Size> <Type>Primary</Type> </CreatePartition> <CreatePartition wcm:action="add"> <Order>3</Order> <Type>Primary</Type> <Extend>true</Extend> </CreatePartition> </CreatePartitions> <ModifyPartitions> <ModifyPartition wcm:action="add"> <Order>1</Order> <PartitionID>1</PartitionID> <Label>System</Label> <Format>NTFS</Format> <Active>true</Active> </ModifyPartition> <ModifyPartition wcm:action="add"> <Order>2</Order> <PartitionID>2</PartitionID> <Letter>C</Letter> <Label>SEVEN</Label> <Format>NTFS</Format> </ModifyPartition> <ModifyPartition wcm:action="add"> <Order>3</Order> <Format>NTFS</Format> <PartitionID>3</PartitionID> <Label>DATA</Label> <Letter>D</Letter> </ModifyPartition> </ModifyPartitions> </Disk> </DiskConfiguration>We can't merge the two methods or strings!