How ASR Works

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

ASR represents a new approach to backup and recovery. Prior to ASR, after a large-scale failure, you needed to reinstall Windows, configure all physical storage to the original settings, and then perform a complete restore of the data. The process of rebuilding the operating system could be lengthy, and you needed to perform many of these tasks at the local computer. ASR significantly automates this process. In addition to automating the restore of a single system, ASR can be used with Remote Installation Services (RIS) to automate the system state recovery of several systems across the network.

To prepare for ASR recovery, you must run the Automated System Recovery Wizard, which is part of Backup. To access this wizard when you are running Backup in Advanced Mode, click Tools and select ASR Wizard. You can start Backup in Advanced Mode by clearing the Always start in Wizard Mode check box when Backup starts.

The wizard backs up the operating system boot volumes and system volumes, but does not back up other volumes, such as program or data volumes. To secure data on other volumes, you must back up those volumes separately by using Backup or another backup tool. You can, however, choose to back up All information on this computer when running Backup. This option creates a full backup of your entire system, including ASR data. This means that you can recover the entire system through the ASR process in the event of failure.

When an ASR restore is initiated, ASR first reads the disk configurations from the ASR floppy disk and restores all disk signatures and volumes on the disks from which the system boots. In the ASR process, these are known as critical disks, because they are required by the operating system. Noncritical disks — disks that might store user or application data — are not backed up as a part of a normal ASR backup, and are not included in an ASR restore. If these disks are not corrupted, their data will still be accessible after the ASR restore completes. If you want to secure data on noncritical disks from disk failure, you can do so by backing it up separately.

After the critical disks are recreated, ASR performs a simple installation of Windows Server 2003 and automatically starts a restore from backup using the backup media originally created by the ASR Wizard. During an ASR restore, any Plug and Play devices on the system are detected and installed.

Before performing an ASR restore, ensure that the target system to which the restore will be made meets the following requirements:

  • The target system hardware (except for hard disks, video cards, and network adapters) is identical to that of the original system.

  • There are enough disks to restore all the critical system disks.

  • The number and storage capacity of the critical disks are at least as great as those of the corresponding original disks.


  • Do not depend on ASR to back up and recover user data files stored on the boot and system volumes. In addition, because your system volume is formatted during the ASR recovery process, any user files or directories located on those volumes are lost.

You normally access the ASR state file (Asr.sif) through a local floppy disk drive. If the computer does not have a floppy disk drive, or you want to perform an ASR restore over a network or remotely, you can use a Remote Installation Services (RIS) server to fully automate the ASR process. RIS uses Pre-boot eXecution Environment (PXE) technology to enable client computers without an operating system to boot remotely to a RIS server that performs installation of a supported operating system over a TCP/IP network connection. Consequently, the remote installation client computer must have a PXE-enabled network adapter.

For more information about using RIS to perform remote installations, see "Designing RIS Installations" in Automating and Customizing Installations of this kit.


  • ASR behaves differently from the Emergency Repair Disk feature in Windows 2000 Server, which ASR replaces. Emergency Repair Disk replaces missing or corrupt system files without formatting drives or reconfiguring storage. ASR, by contrast, always formats the boot volume and might format the system volume.