Because hardware occasionally fails and, in the real world, operating systems do have problems, a server-recovery plan is essential, even though it might never be used. The last thing any administrator wants is for a server failure to occur and to end up on the phone with Microsoft technical support asking for the server to be restored from backup when no plan is in place. To keep from being caught unprepared, the administrator should have a recovery plan for every possible failure associated with Windows Server 2003 systems.
When a complete system failure occurs, whether it is due to a site outage, a hardware component failure, or a software corruption problem, the method of recovery depends on the administrator's major goal. The goal is to get the server up and running, of course, but behind the scenes, many more questions should be answered before the restore is started:
How long will it take to restore the server from a full backup?
If the server failed due to software corruption, will restoring the server from backup also restore the corruption that actually caused the failure?
Will reloading the operating system and Exchange manually followed by restoring the system state be faster than doing a full restore?
Loading the Windows Server 2003 operating system and Exchange Server 2003 software can be a relatively quick process. This ensures that all the correct files and drivers are loaded correctly and all that needs to follow is a system state restore to recover the server configuration and restore the data. One of the problems that can occur is that, upon installation, some applications generate Registry keys based on the system's computer name, which can change if a system state restore is performed.
Exchange Server 2003 has a setup /disasterrecovery installation option and does not need the server's system state restore—just the original computer name and domain membership, as long as computer and user certificates are not being used.
The key to choosing whether to rebuild or restore from backup is understanding the dependencies of the applications and services to the operating system, and having confidence in the server's stability at the time of the previous backups. The worst situation is attempting a restore from backup that takes several hours, only to find that the problem has been restored as well.
When a complete server system failure is encountered and the state of the operating system or an application is in question, the operating system can be recovered manually. Locating the system's original configuration settings is the first step. This information is normally stored in a server build document or wherever server configuration information is kept.
Because each system is different, as a general guideline for restoring a system manually, perform the following steps:
NOTE
If certificates were issued to the previous server, the new server must enroll with the Certificate Authority (CA) for a new certificate before encrypted communication can occur.
The restoration of an Exchange Server 2003 system into an existing Active Directory domain does not require the installation of the system state because the procedures covered in the previous section will recover the server and database for the server replacement. However, if the failure of Exchange also included the loss of the Active Directory Global Catalog and there is no other Global Catalog in the organization, a system state restore of the Global Catalog needs to be performed before Exchange can be restored.
Exchange Server 2003 requires a valid Active Directory to be in place. This process might be required if the Exchange server was the only server in the network and, thus, the loss of the Exchange server also meant the loss of the only Global Catalog server. This also might be the case if there was a site failure and all servers, including the Exchange Server and Active Directory Global Catalog server, were lost.
To recover the system state, follow these steps:
After all the updates have been installed, restore the previously backed-up system state data; afterward, restore any additional application or user data.
This section outlines how to restore the system state to a member or standalone Windows Server 2003 system. To restore the system state, perform the following steps:
1. | Click Start, All Programs, Accessories, System Tools, Backup. |
2. | If this is the first time you've run Backup, it opens in Wizard mode. Choose to run it in Advanced mode by clicking the Advanced Mode hyperlink. |
3. | Click the Restore Wizard (Advanced) button to start the Restore Wizard. |
4. | Click Next on the Restore Wizard welcome screen to continue. |
5. | On the What to Restore page, select the appropriate cataloged backup medium, expand the catalog selection, and check System State. Click Next to continue. |
6. | |
7. | On the Completing the Restore Wizard page, click Finish to start the restore. The restore will look something similar to Figure 32.2. Figure 32.2. Performing a system state restore on an Exchange server. |
8. | When the restore is complete, review the backup log for detailed information and click Close on the Restore Progress window when finished. |
9. | Reboot the system as prompted. |
10. | When the system restarts, log in using an account with Local and/or Domain Administrator rights, as necessary. |
11. | After the system state is restored, Exchange Server 2003 can be installed. |
When a system has failed and all other recovery options have been exhausted, an Automated System Recovery (ASR) restore can be performed, provided that an ASR backup has been previously performed. The ASR restore will restore all disk and volume configurations, including redefining volumes and formatting them. This means that the data stored on all volumes needs to be restored after the ASR restore is complete. This restore brings a failed system back to complete server operation, except for certain applications that require special configurations after the restore. For example, the Remote Storage service data needs to be restored separately.
NOTE
An ASR restore re-creates all disk volumes, but if a new or alternate system is being used, each disk must be of equal or greater size to the disks on the original server. Otherwise, the ASR restore will fail.
To perform an ASR restore, follow these steps:
When a Windows Server 2003 system is recovered using an ASR restore, the boot.ini file might not be restored. This file contains the options for booting into different operating systems on multiboot systems and booting into the Recovery Console if it was previously installed. To restore this file, simply restore it from backup to an alternate folder or drive. Delete the boot.ini file from the C: root folder and move the restored file from the alternate location to C: or whichever drive the boot.ini file previously was located on.