- Do not install Windows 7 to a hard disk that not yet been partitioned or to unallocated space (When install Windows 7 to unallocated space, no warning pop-up or confirmation is asked, and setup will straight away and directly create partition 200 MB of disk space as special partition without notification).
- If possible, try to create all the necessary partition(s) and format the partition(s) before attempting to install Windows 7.
- If you’re installing Windows 7 into a new hard disk, or a blank hard disk with no partition defined yet, or if you must delete all existing partitions to start afresh, chose Drive options (advanced). Delete (if applicable) unwanted partitions. Then, click New to create the single partition or multiple partitions according to your own preference.
When prompted with dialog box saying “To ensure that all Windows features work correctly, Windows might create additional partitions for system files”, click on Cancel button. Optionally, to be double confirm, Format the partition before selecting it to install Windows 7.
If you follow the install instructions in the first three paragraphs of the section How to Install Vista and Avoid Changes to Other Operating Systems, it will produce the same results for Win7 public release. You should however disregard the forth paragraph in that section as there has been a major change to the way the Win7 setup will handle free space. If you point the Win7 install to unpartitioned space in a machine that does not already have an active primary partition on the boot hard drive, then setup will without any notification create an extra small partition just for the main boot files to reside on. This partition will be a small 100MB primary on the boot hard drive and it will become the active System partition to the Boot partition of your new Win7 install. The files placed on this tiny partition will be bootmgr and the Boot folder, (and bootsect.bak, a backup of the PBR). The partition will be labelled as ‘System Reserved’ and will not be mounted or assigned a drive letter inside Windows7 so most users will not be aware of its existence. The operating system will not have those boot files on its own partition, which will have obvious consequences for imaging and cloning.
If you already have three primary partitions that are either hidden or of an unsuitable file system, then the Windows setup will fail if you point it to remaining unpartitioned space. The Win7 setup will want to create 2 primary partitions and this exceeds the maximum allowance of 4. “Setup was unable to create a new system partition or locate an existing partition.” If one of the 3 existing primaries is visible and suitable then setup will accept the unpartitioned space and set the existing primary as active and use it as the system partition. If more than one suitable primary is visible then setup will choose either an already active partition or the first suitable primary from the start of the hard drive. If an unsuitable primary was the active one then it will lose that status.