When you install from the Solaris 8 Installation CD and you choose a swap slice that is not on the default boot disk, the Default Install selection might be disabled. This problem can occur even when the swap slice starts at cylinder 0 and the default boot disk contains sufficient space for a Default Install. The following error message is displayed.
Note:Default install is not possible.The file system requires manual layout.
If you are performing an initial install, choose the default boot disk as the location for the swap slice.
Perform a Custom Install if your swap slice is not located on the default boot disk.