BCD Stores

Physically, a BCD store is a binary file in the registry hive format. A computer has a system BCD store that describes all installed Windows Vista and Windows 7 operating systems and installed Windows boot applications. A computer can optionally have many non-system BCD stores. Figure below shows an example of how the BCD hierarchy is implemented in a typical BCD store.

A BCD store normally has at least two (and optionally, many) BCD objects:

• A Windows Boot Manager object This object contains BCD elements that pertain to the Windows Boot Manager, such as the entries to display in an operating system selection menu, boot tool selection menu, and time-out for the selection menus. The Windows Boot Manager object and its associated elements serve essentially the same purpose as the [boot loader] section of a Boot.ini file. A store can optionally have multiple instances of the Windows Boot Manager. However, only one of them can be represented by the Windows Boot Manager well-known globally unique identifier (GUID). You can use the GUID's alias, {bootmgr}, to manipulate a store with BCDEdit.
• At least one and optionally several Windows Boot Loader objects Stores contain one instance of this object for each version or configuration of Windows Vista, Windows Server 2008, or Windows 7 that is installed on the system. These objects contain BCD elements that are used when loading Windows or during Windows initialization such as no-execute (NX) page protection policy, physical address extension (PA E) policy, and kernel debugger settings. Each object and its associated elements serve essentially the same purpose as one of the lines in the [operating systems] section of Boot.ini. When a computer is booted into Windows, the alias {current} represents the associated boot loader object. When manipulating a store with BCDEdit, the default boot loader object has the alias {default}.
• An optional Windows {ntldr} object The {ntldr} object describes the location of Ntldr, which you can execute to boot Windows XP or earlier versions of Windows. This object is required only if the system includes versions of Windows that are earlier than Windows Vista. It is possible to have multiple instances of objects that describe Ntldr. However, as with the Windows Boot Manager, only one instance can be represented by the {ntldr} well-known GUID alias. You can use the GUID's alias, {ntldr}, to manipulate a store with BCDEdit.
• Optional boot applications Stores can optionally have BCD objects that perform other boot-related operations. One example is the Windows Memory Tester, which runs memory diagnostics.