Windows 7 / Getting Started

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.

The BCD hierarchy allows for multiple boot options

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.
[Previous] [Contents] [Next]

In this tutorial:

  1. Configuring Startup and Troubleshooting Startup Issues
  2. What is New with Windows Startup
  3. Boot Configuration Data
  4. BCD Stores
  5. System Recovery
  6. Windows Boot Performance Diagnostics
  7. Understanding the Startup Process
  8. Power-on Self Test Phase
  9. Initial Startup Phase
  10. Initial Startup Phase for BIOS Computers
  11. Initial Startup Phase for EFI Computers
  12. Windows Boot Manager Phase
  13. Windows Boot Loader Phase
  14. Kernel Loading Phase
  15. Control Sets
  16. Values for the Start Registry Entry
  17. Value Descriptions for Type Entries
  18. Other Registry Entries in the Servicename Subkeys
  19. Session Manager
  20. Logon Phase
  21. Important Startup Files
  22. How to Configure Startup Settings
  23. How to Use the Startup And Recovery Dialog Box
  24. How to Use the System Configuration Tool
  25. How to Use BCDEdit
  26. How to Interpret BCDEdit Output
  27. How to Back Up and Restore Settings
  28. How to Change the Default Operating System Entry
  29. How to Change the Boot Menu Time-Out
  30. How to Change the Order of Boot Manager Menu Items
  31. How to Create an Entry for Another Operating System
  32. How to Remove a Boot Entry
  33. How to View and Update Global Debugger Settings
  34. How to Remove the Windows 7 Boot Loader
  35. How to Configure a User Account to Automatically Log On
  36. How to Disable the Windows Startup Sound
  37. How to Speed Up the Startup Process
  38. The Process of Troubleshooting Startup
  39. Startup Troubleshooting Before the Starting Windows Logo Appears
  40. How to Start the System Recovery Tools
  41. How to Run Startup Repair
  42. How to Use BootRec.exe
  43. How to Diagnose Hardware Problems
  44. How to Use System Restore
  45. How to Manually Repair the Boot Sector
  46. How to Manually Update the BCD Registry File
  47. How to Manually Replace Files
  48. How to Reinstall Windows
  49. Startup Troubleshooting After the Starting Windows Logo Appears
  50. How to Restore the Last Known Good Configuration
  51. How to Enable Boot Logging
  52. How to Start in Safe Mode
  53. How to Identify Failing Drivers and Services
  54. How to Analyze Startup Problems in Safe Mode
  55. Event Viewer (Eventvwr.msc)
  56. System Information
  57. Error Reporting Service
  58. How to Use Device Manager to View or Change Resources
  59. How to Analyze Boot Logs
  60. How to Roll Back Drivers
  61. How to Temporarily Disable a Service
  62. Troubleshooting Startup Problems After Logon
  63. How to Temporarily Disable Startup Applications and Processes
  64. How to Disable Startup Applications Using the Shift Key
  65. How to Disable Startup Programs Using the System Configuration Utility
  66. How to Disable Startup Applications Configured Using Group Policy or Logon Scripts
  67. How to Permanently Disable Startup Applications and Processes
  68. Manually Remove the Entry