System-Level Fault Tolerance (Clustering/Network Load Balancing) - Cluster Node Backup Best Practices
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As a backup best practice for cluster nodes, administrators should strive to back up everything as frequently as possible. Because cluster availability is so important, here are some recommendations for cluster node backup:
Back up each cluster node's system state daily and immediately before and after a cluster configuration change is made.
Back up cluster local drives and system state daily if the schedule permits or weekly if daily backups cannot be performed.
Back up cluster shared drives daily if the schedule permits or weekly if daily backups cannot be performed.
Use the MSCS Recovery Utility (ClusterRecovery) utility provided in the Windows Server 2003 Resource Kit to save configuration information such as checkpoint files. These checkpoint files are stored in the quorum but are still used to update Registry settings when resources are moved or failed over to another cluster node.
Perform an ASR backup on each node following the creation of a new cluster, monthly, and whenever a change is made on the node. For instance, back up when a new cluster application is installed or when a disk is added or removed from a cluster.
Automated System Recovery Backup
Automated System Recovery has two parts: the ASR backup and the ASR restore. An ASR backup can be used to satisfy one of a cluster node's backup requirements, backing up disk signatures and volume information. When a disk signature is overwritten and the cluster can no longer identify shared disks or read volume information, the administrator needs to restore cluster disk signatures using ASR restore. This approach, however, is a last resort and should be used only if no cluster nodes can communicate with the shared devices and all other cluster restore techniques have been exhausted.
An ASR backup of a cluster node contains a disk signature or signatures and volume information; the current system state, which includes the Registry, cluster quorum, boot files, and the COM+ class registration database; system services; and a backup of all local disks containing operating system files, including system and boot partitions. Currently, the only way to back up disk signatures is to create an ASR backup from the local server console using Windows Server 2003 Backup.
To perform an ASR backup, an administrator needs a blank floppy disk and a backup device; either a tape device or disk will suffice. Using recordable CDs and devices for use with the Backup utility is not yet supported, so if no tape device is available, the backup can be run to a backup file on a local or a network drive. Saving the backup file to a network drive helps to ensure that the media can be accessed when an ASR restore is necessary. One point to keep in mind is that an ASR backup will back up each local drive that contains the operating system and any applications installed. For instance, if the operating system is installed on drive C: and MS Office is installed on drive D:, both of these drives will be completely backed up. Although this can greatly simplify restore procedures, it requires additional storage and increases backup time. Using a basic installation of Windows Server 2003 Enterprise server with only the Cluster Service installed, an ASR backup averages 1.3GB in size.
To create an ASR backup, perform the following steps:
Log on to the cluster node with an account that has the right to back up the system. (Any Local Administrator, Domain Administrator, or Cluster Service account has the necessary permissions to complete the operation.)
Click Start, All Programs, Accessories, System Tools, Backup.
If this is the first time you've run Backup, it will open in Wizard mode. Choose to run it in Advanced mode by clicking the Advanced Mode hyperlink. After you change to Advanced mode, the window should look similar to Figure 31.13.
Click the Automated System Recovery Wizard button to start the Automated System Recovery Preparation Wizard.
Click Next after reading the Automated System Recovery Preparation Wizard Welcome screen.
Choose your backup media type and choose the correct media tape or file. If you're creating a new file, specify the complete path to the file, and the backup will create the file automatically. Click Next to continue.
If the file you specified resides on a network drive, click OK at the warning message to continue, as shown in Figure 31.14.
Figure 31.13 Windows Backup in Advanced mode.
Figure 31.14 Warning when selecting a resource for backup.
Click Finish to complete the Automated System Recovery Preparation Wizard and to start the backup.
After the tape or file backup portion completes, the ASR backup prompts you to insert a floppy disk that will contain the recovery information. Insert the disk and click OK to continue.
Remove the floppy disk as requested and label the disk with the appropriate ASR backup information. Click OK to continue.
When the ASR backup is complete, click Close on the Backup Progress windows to return to the backup program or click Report to examine the backup report.
ASR backups should be performed periodically and immediately following any hardware changes to a cluster node, including changes on a shared storage device or local disk configuration. The information contained in the ASR floppy disk is also stored on the backup media. The ASR floppy contains two files, asr.sif and asrpnp.sif, that can be restored from the backup media and copied to a floppy disk when an ASR restore is necessary.
Backing Up the Cluster Quorum
The cluster quorum is backed up when the system state of any active cluster node is backed up. This backup can be used to restore a cluster node to operation when cluster database or log corruption occurs or when the previous state of a cluster needs to be rolled back up to every cluster node. The cluster quorum should be backed up frequently to ensure that the latest version of the cluster configuration is saved. To back up the cluster quorum, follow the steps outlined in the next section.
 This chapter is from Microsoft Windows Server 2003 Unleashed, by Rand Morimoto, et al. (Sams Publishing, 2004, ISBN: 0672326671). Check it out at your favorite bookstore today.
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