Identifying the Extent of the Problem

Before a successful recovery can be conducted , the extent of the problem must be determined. Different recovery strategies exist for recovering a lost mail message or folder than for recovering an entire mailbox. There are different recovery strategies for recovering a corrupt mailbox and for recovering an entire failed server. Using the right recovery process to solve the right problem requires the problem-resolution process to minimize the recovery time and the chance that a simple recovery will create bigger problems in the process.

In case of a system failure, many organizations try to recover the entire server. Depending on the amount of data, this could take several hours to get the system completely operational. Before beginning the process of restoring the entire server, it is important to analyze the amount of data that needs to be recovered, as well as the existing conditions of recovery methods . There is no need to restore from tape if the Recovery Storage Group option has been enabled on Exchange and can be used as part of the recovery process. Also, a full restore of a corrupt database on tape does not resolve the problem of a corrupt database on the server hard drive. Identifying what the problem is provides the best method for restoration.

Mailbox Content Was Deleted, Use the Undelete Function of Exchange

When information is deleted from a user's mailbox, whether it is an email message, a Calendar appointment, a contact, or a task, the information is not permanently deleted from the Exchange server. Deleted items go into the Deleted Items folder in the user 's Outlook mailbox. The information is actually retained on the Exchange server for 30 days after deletion, even when it is supposedly permanently deleted from the Deleted Items folder.

NOTE

The Mail Retention feature needs to be enabled on the Exchange Server for Outlook information to be retained on the Exchange server.

Data Is Lost, Must Restore from Backup

If data is lost and the undelete function will not recover the information, the information needs to be restored from a backup. Depending on how much information was lost, this might involve a full recovery of the Exchange server from tape, or it might involve restoring just a single mailbox, folder, or message. Key to restoring information is determining what needs to be restored. If just a single message needs to be restored, there is no reason to recover the entire server in production. In many cases, when full tape backups have been conducted of an Exchange server, a full restore must be completed offline and then a specific mailbox, folder, or mail message must be extracted from the offline restored server to the production server. The restore process needs to take in account the restoration of the information desired without the restoration of the entire server, which might overwrite valid data.

The process of restoring all or partial data from tape is covered in the sections "Recovering from a Complete Server Failure" and "Recovering from Database Corruption," later in this chapter.

Data Is Okay, Server Just Doesn't Come Up

The failure of a server does not necessarily mean that the data needs to be restored completely from tape. In fact, if the hard drives on a dead server are still operational, the hard drives should be moved to an operational server or, at the very least, the data should be transferred to a different server. By preserving the data on the drives , an organization can minimize the need to perform more complicated data reconstruction from a tape restore, which could result in the loss of data from the time of the last backup.

The process of recovering data from a drive and recovering a failed server is covered in the section "Performing a Restore of Only Exchange Database Files," later in this chapter.

Data Is Corrupt ”Some Mailboxes Are Accessible, Some Are Not

Data corruption commonly occurs on Exchange servers, not because Exchange is particularly an unreliable system, but because Exchange data is stored in a database that requires periodic maintenance. Without periodic maintenance, covered in Chapter 19, "Exchange Server 2003 Management and Maintenance Practices," the databases in Exchange become corrupt. Exchange database corruption that is not repaired can make portions of mailboxes stored on an Exchange server inaccessible.

When recovering from data corruption on an Exchange server, it is important to not only recover lost or inaccessible data, but also to also repair the database, to prevent existing data corruption from causing more problems on an Exchange server in the future.

When a mailbox or multiple mailboxes are corrupt, the good data in the mailboxes can be extracted with minimal data loss. By isolating the corruption and extracting good data, an organization that might not need to recover the lost data can typically continue to operate with minimal downtime.

The process of extracting mail from an Exchange database is covered in the section "Recovering from Database Corruption," later in this chapter.

Data Is Corrupt, No Mailboxes Are Accessible

Depending on the condition of an Exchange database, the information might be so corrupt that none of the mailboxes are accessible. Recovering data from a corrupt database that cannot be accessed is a two-step process. The first step is to conduct maintenance to attempt to get the database operational; the second step is to extract as much information from the database as possible.

The process of performing maintenance and extracting data from a corrupt database is covered in the section "Recovering from Database Corruption," later in this chapter.

Exchange Server Is Okay, Something Else Is Preventing Exchange from Working

If you know that the Exchange server and databases are operational and something else is preventing Exchange from working, the process of recovery focuses on looking at things such as Active Directory, Internet Information Server (IIS), the Domain Name System (DNS), and the network infrastructure, as with site-to-site connectivity for replication.

The process of analyzing the operation of other services is covered in the sections "Recovering Windows Server 2003 Domain Controllers" and "Recovering Active Directory," later in this chapter.