Recovering from a Disaster in an Exchange Server 2007 Environment : Recovering from a Boot Failure & Recovering from a Complete Server Failure

4/11/2012 4:37:37 PM

Recovering from a Boot Failure

Occasionally, a Windows Server 2003 system can suffer a service or application startup problem that could leave a server incapable of completing a normal bootup sequence. Because the operating system cannot be accessed in this case, the system remains unavailable until this problem can be resolved.

Windows Server 2003 includes a few alternative bootup options to help administrators restore a server to a working state. Several advanced bootup options can be accessed by pressing the F8 key when the boot loader screen is displayed. If the Recovery Console was previously installed, it is listed as an option in the boot loader screen. The advanced boot options include the following:

Safe Mode— This mode starts the operating system with only the most basic services and hardware drivers, and disables networking. This allows administrators to access the operating system in a less functional state to make configuration changes to service startup options, some application configurations, and the system Registry.
Safe Mode with Networking— This option is the same as Safe Mode, but networking drivers are enabled during operation. This mode also starts many more operating system services upon startup.
Safe Mode with Command Prompt— This option is similar to the Safe Mode option; however, the Windows Explorer shell is not started by default.
Enable Boot Logging— This option boots the system normally, but all the services and drivers loaded at startup are recorded in a file named ntbtlog.txt, located in the %systemroot% directory. The default location for this file is C:\Windows\ntbtlog.txt. To simplify reading this file, the administrator must delete the existing file before a bootup sequence is logged so that only the information from the last bootup is logged.
Enable VGA Mode— This mode loads the current display driver, but it displays the desktop at the lowest resolution. This mode is handy if a server is plugged into a different monitor that cannot support the current resolution.
Last Known Good Configuration— This mode starts the operating system using Registry and driver information saved during the last successful logon.
Directory Services Restore Mode— This mode is only for domain controllers and allows for maintenance and restoration of the Active Directory database or the SYSVOL folder.
Debugging Mode— This mode sends operating system debugging information to other servers through a serial connection. This requires a server on the receiving end with a logging server that is prepared to accept this data. Most likely, standard administrators will never use this mode.
Start Windows Normally— As the name states, this mode loads the operating system as it would normally run.
Reboot— This option reboots the server.
Return to OS Choices Menu— This option returns the screen to the boot loader page so that the correct operating system can be chosen and started.

The Recovery Console

The Recovery Console provides an option for administrators to boot up a system using alternate configuration files to perform troubleshooting tasks. Using the Recovery Console, the bootup sequence can be changed, alternate boot options can be specified, volumes can be created or extended, and service startup options can be changed. The Recovery Console has only a limited number of commands that can be used, making it a simple console to learn. If Normal or Safe Mode bootup options are not working, the administrator can use the Recovery Console to make system changes or read the information stored in the boot logging file using the type command. The boot logging file is located at C:\Windows\ntbtlog.txt by default and exists only if someone tried to start the operating system using any of the Safe Mode options or the boot logging option.

Recovering from a Complete Server Failure

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.

Restoring Versus Rebuilding

When a complete system failure occurs, whether it is because of 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 because of 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 2007 has a setup /recoverserver 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. Using this switch also prevents the Exchange computer from creating the default storage groups and databases. This simplifies the process of restoring the server later.

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.

Manually Recovering a Server

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:

1.	Install a new operating system on the original system hardware and disk volume, or one as close to the original configuration as possible. Be sure to install the same operating system version—for example, Windows Server 2003, Enterprise or Standard Edition.
2.	During installation, name the system using the name of the original server, but do not join a domain.
3.	Do not install additional services during installation, and proceed by performing a basic installation.
4.	When the operating system completes installation, install any additional hardware drivers as necessary and update the operating system to the service pack and security patches that the failed server was expected to have installed. To reduce compatibility problems, install the service packs and updates as outlined in the server build document to ensure that any installed applications will function as desired. During a restore is not the time to roll out additional system changes. The goal is to get the system back online, not to upgrade it.
5.	Using the Disk Management console, create and format disk volumes and assign the correct drive letters as recorded in the server build document.
6.	If the server was originally part of a domain, join the domain using the original server name. Because many Windows Server 2003 services use the server name or require the service to be authorized in a domain, perform this step before installing any additional services or applications.
7.	Install any additional Windows Server 2003 services as defined in the server build document.
8.	Install Exchange Server 2007 using the same version of Exchange (Standard or Enterprise) that was originally installed. Apply any Exchange service packs and updates that were expected to be on the original server as well. When installing Exchange, use the setup /recoverserver installation process that will install Exchange but will not add new databases.
9.	Restore Exchange data to the new server.
10.	Test functionality, add this system to the backup schedule, and start a full backup.

Note

If certificates were issued to the previous server, the new server must import the same certificates or enroll with the certificate authority (CA) for a new certificate before encrypted communication can occur.

Restoring a Server Using a System State Restore

The restoration of an Exchange Server 2007 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 2007 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:

1.	Shut down the original server or build a new server hardware system.
2.	Install a new copy of Windows Server 2003 on the system hardware and disk volume, or one as close to the original configuration as possible. Be sure to install the same operating system version—for example, Windows Server 2003, Enterprise or Standard Edition.
3.	During installation, name the system using the name of the original server, but do not join a domain. Note If the machine is joined to the original domain during the clean installation, a new security identifier (SID) will be generated for the machine account. A System State restore after this restores an invalid computer SID, and many services and applications will fail.
4.	Do not install additional services during installation, and proceed by performing a basic installation.
5.	When the operating system completes installation, install any additional hardware drivers as necessary and update the operating system to the latest service pack and security patches. To reduce compatibility problems, install the service packs and updates as outlined in the server build document, to ensure that any installed applications will function as desired.
6.	Using the Disk Management console, create and format disk volumes and assign the correct drive letters as recorded in the server build document.
7.	After the installation, restore any necessary drivers or updates to match the original configuration. This information should be gathered from a server configuration document (server build document). Then reboot as necessary.

After all the updates have been installed, restore the previously backed-up System State data; afterward, restore any additional application or user data.

System State Restore

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.	If the correct tape or file backup medium does not appear in this window, cancel the restore process. Then, from the Restore Wizard, locate and catalog the appropriate medium and return to the restore process from step 1.
7.	On the Completing the Restore Wizard page, click Finish to start the restore. The restore will look similar to Figure 33.1. Figure 33.1. Performing a 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 on using an account with local and/or domain Administrator rights, as necessary.
11.	After the System State is restored, Exchange Server 2007 can be installed.

Restoring a System Using an Automated System Recovery Restore

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:

1.	Locate the ASR floppy created for the failed node, or create the floppy from the files saved in the ASR backup medium. For information on creating the ASR floppy from the ASR backup medium, refer to Help and Support from any Windows Server 2003 Help and Support tool.
2.	Insert the Windows Server 2003 operating system medium in the CD-ROM drive of the server to which you are restoring, and start the installation from this CD.
3.	When prompted, press F6 to install any third-party storage device drivers, if necessary. This includes any third-party disks or tape controllers that Windows Server 2003 will not natively recognize.
4.	Press F2 when prompted to perform an Automated System Recovery.
5.	Insert the ASR floppy disk into the floppy drive, and press Enter when prompted. If the system does not have a local floppy drive, one must temporarily be added; otherwise, an ASR restore cannot be performed.
6.	The operating system installation proceeds by restoring disk volume information and reformatting the volumes associated with the operating system. When this process is complete, the operating system will restart after a short countdown, the graphic-based OS installation will begin, and the ASR backup will attempt to reconnect to the backup medium automatically. If the backup medium is on a network drive, the ASR backup reconnection will fail. If it fails, specify the network location of the backup medium using a Universal Naming Convention (UNC) path, and enter authentication information, if prompted.
7.	When the medium is located, open the medium, click Next, and then click Finish to begin recovering the remaining ASR data.
8.	When the ASR restore is complete, if any local disk data was not restored with the ASR restore, restore all local disks.
9.	Click Start, All Programs, Accessories, System Tools, Backup.
10.	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.
11.	Click the Restore Wizard (Advanced) button to start the Restore Wizard.
12.	Click Next on the Restore Wizard welcome screen to continue.
13.	On the What to Restore page, select the appropriate cataloged backup medium, expand the catalog selection, and check the desired data on each local drive. Click Next to continue.
14.	On the Completing the Restore Wizard page, click Finish to start the restore. Because you want to restore only what ASR did not, you do not need to make any advanced restore configuration changes.
15.	When the restore is complete, reboot the server, if prompted.
16.	After the reboot is complete, log on to the restored server and check server configuration and functionality.
17.	If everything is working properly, perform a full backup and log off the server.

Restoring the Boot Loader File

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 was previously located on.