- Optimizing Disk Management for Fault Tolerance
- Maximizing Redundancy and Flexibility with Distributed File System
- Simplifying Fault Tolerance with Volume Shadow Copy
- Optimizing Disk Utilization with Remote Storage
- Optimizing Clusters to Simplify Administrative Overhead
- Leveraging Network Load Balancing for Improved Availability
- Realizing Rapid Recovery Using Automated System Recovery (ASR)
- Summary
This chapter is from the book
This chapter is from the book
This chapter is from the book
Realizing Rapid Recovery Using Automated System Recovery (ASR)
Another new feature of Windows Server 2003 is Automated System Recovery (ASR). ASR is more a recovery feature than a fault-tolerance tool, although in an effort to increase server availability in the event of a disaster, ASR can be a valuable component to the overall solution.
The primary goal of ASR is to accelerate recovery time in the event of the loss of a server by bringing a nonbootable system to a state from which a backup and restore application can be executed. This includes configuring the physical storage to its original state, and installing the operating system with all the original settings.
Improving the Disaster Recovery Process
Prior to Windows Server 2003, the process by which a lost server is rebuilt and recovered was a time-consuming ordeal. The old methods usually resembled the following process:
The administrator gets new hardware.
Windows is reinstalled from installation media.
Physical storage is manually configured to match original system.
Backup and restore application and drivers are installed.
The original operating system is manually restored to restore settings.
The server is rebooted, and services are manually adjusted.
Data is restored.
With ASR, many of the steps in the old model are eliminated or automated. The new recovery method now proceeds as follows:
The administrator gets new hardware.
From the Windows CD, the administrator executes ASR (by pressing F2 on startup).
The administrator inserts other media when prompted.
Data is restored.
ASR is broken down into two parts: backup and restore. The backup portion is executed through the Automated System Recovery Preparation Wizard located in Backup. The Automated System Recovery Preparation Wizard backs up the System State data, system services, and all disks associated with the operating system components. It also creates a floppy disk, which contains information about the backup, the disk configurations (including basic and dynamic volumes), and how to accomplish a restore.
The restore portion of ASR is initiated by pressing F2 during the text portion of Windows Server 2003 setup. When the ASR restore process is initiated, ASR reads the disk configurations from the floppy disk and restores all the disk signatures, volumes, and partitions on the disks required to start your computer. ASR then installs a simple installation of Windows and automatically starts to restore from backup using the backup ASR set created by the Automated System Recovery Preparation Wizard.
A Full Data Backup
ASR is primarily involved with restoring the system; it does not back up data. Always include a full data backup in disaster recovery solutions.
To take advantage of ASR in a disaster recovery solution, systems must meet a limited set of requirements:
Similar hardware. The restored server must have identical hardware to the original server with the exception of network cards, video cards, and hard drives.
Adequate disk space. Obviously, the restored server must have adequate disk space to restore all critical disks from the original server. Disk geometries must also be compatible.
ASR state file (asr.sif) must be accessible from a floppy. ASR requires a local floppy drive access. Remote or network recovery procedures do not work with ASR.
ASR supports FAT volumes of 2.1GB maximum. For volumes larger than 2.1GB, the volume should be formatted with NTFS.
Using ASR to Recover Cluster Services
ASR can be used to recover a cluster node that is damaged because of corrupt or missing system files, cluster registry files, or hard disk failure. To prepare for an ASR recovery of clustered servers, run the Automated System Recovery Preparation Wizard on all nodes of the cluster and make sure that the cluster service is running when the Automated System Recovery backup is run. Make sure that one of the nodes on which the Automated System Recovery Preparation Wizard is run is listed as the owner of the quorum resource while the wizard is running.
In addition to having the ASR disk, recovering a damaged node in a cluster requires the Windows Server 2003 installation media, backup media containing data backup, and potentially the mass storage driver for the new hardware. With these in hand, perform the following steps to recover a damaged cluster node:
Insert the original operating system installation CD into the CD drive of the damaged cluster node.
Restart the computer. If prompted to press a key to start the computer from CD, press the appropriate key.
If there is a separate driver file for the mass storage device, press F6 when prompted to use the driver as part of setup.
Press F2 when prompted during the text-only mode section of Setup. This will generate a prompt for the ASR disk.
Follow the directions on the screen.
If there is a separate driver file for the mass storage device, press F6 (a second time) when prompted after the system reboots.
Follow the directions on the screen.
After all the restore steps have completed, the restored node can rejoin the cluster.
Restoring a Disk Signature to a Damaged Cluster Disk
If you are restoring a disk signature to a damaged cluster disk, power down all other cluster nodes except the one on which you are performing the ASR restore. This cluster node must have exclusive rights to the damaged cluster disk.