Exchange provides the following methods for database backup:

• Legacy streaming backup   The first method is the legacy streaming backup using the Extensible Storage Engine (ESE) application programming interface (API). The streaming backup technology is used by Microsoft Windows Server Backup as well as many third-party products. This technology has been available in all previous versions of Exchange and has a mature feature set.
  
• Volume Shadow Copy Service    Support for Volume Shadow Copy Service (VSS) was introduced in Exchange Server 2003 and enhanced extensively in Exchange 2007. Microsoft does not provide an Exchange-aware VSS-based backup solution. The Windows Server Backup utility does not support VSS. Backup can take VSS shadow copies of the Exchange database and log files, but this is done at the file level. These copies are not Exchange-aware backups. Third-party backup software is required to back up the Exchange database with VSS. You must buy an Exchange-aware backup solution to take advantage of VSS functionality.
  For more information, see Exchange 2007 Data Backup and Volume Shadow Copy Services and the Exchange Server Team Blog article So what is this "shadow copy" Exchange backup that NTBackup can take.
  

  Note:
  The content of each blog and its URL are subject to change without notice. The content within each blog is provided "AS IS" with no warranties, and confers no rights. Use of included script samples or code is subject to the terms specified in the Microsoft Terms of Use.

In designing your backup process, keep in mind the following:

• Resources required to back up your data, such as CPU and I/O load on the server, and bandwidth to stream your backups off the server.
  
• Duration of the backup window because backups are resource intensive and can affect user performance.
  
• Recovery point objectives. For example, consider how much data you must recover. If the loss of more than one day's worth of data is not acceptable, we recommend daily backups.
  
• Recovery service level agreements (SLAs) that you have established.
  

These considerations, when combined with the backup application you are using, will give you an estimate of the overall database size limitations that you should impose. Databases should not be larger than can be backed up or restored in the time window allowed by your SLAs without adversely affecting users' performance.

With Exchange 2007, you can have a duplicate copy of the database using LCR, CCR and with Exchange 2007 Service Pack 1 (SP1), you can have multiple duplicate copies with SCR. These copies can be used to replace the active database in the event that the active database is unavailable, and serve as the fast recovery solutions for various scenarios that required database restores from backups in the past. Exchange 2007 takes advantage of the second copy of the database and transaction log file in CCR and LCR by providing the ability to take VSS backups from the copy location as opposed to the active database, which in turn provides the following:

• Reduces the load on the production database because all the backup I/O traffic is directed toward the copy location.
  
• Increases the backup window because backup traffic does not affect the client response times.
  
• Increases the database maintenance window because maintenance can take place against the active copy while backups are in progress on the passive copy.
  
• Enables larger databases, due to a larger backup window, which enables a larger mailbox quota.
  

LCR, CCR and SCR copies reduce the need to take frequent full backups because the copies serve as the primary fast recovery solution, leaving restores from backups for second degree failures.

Backup types are divided into the categories of complete backups and change-only backups as follows:

Complete Backups

• Full backup   A full backup is a complete backup that archives every selected database and all necessary log files. Log files older than the checkpoint at the time the backup was started are deleted after the backup completes. If you perform a full backup on a daily basis, you can prevent log files from consuming space on the hard disk.
  

  Important:
  We recommend that you perform daily full backups unless your databases are replicated continuously. For storage groups enabled for LCR, CCR, or SCR, weekly full backups are recommended.

• Copy backup   A copy backup is a complete backup and is the same as a full backup except that log files are not deleted at the completion of the backup. You can perform a copy backup if you want to save a copy of your Exchange databases at a specific point in time.
  

Change-Only Backups

• Incremental backup   An incremental backup is a change-only backup that only archives the transaction log files since the last full or incremental backup. Log files older than the checkpoint are deleted after the backup is complete. You cannot perform an incremental backup when circular logging is enabled. To restore data from an incremental backup, you must have the most recent full backup and each subsequent incremental backup set available. After the restore process is complete, the transaction logs are applied to the Exchange database that you restored with the full backup.
  
• Differential backup   A differential backup is a change-only backup that only archives the transaction log files since the last full or incremental backup. The transaction logs are not deleted. You cannot perform a differential backup when circular logging is enabled. To restore data from a differential backup, you must have the most recent full and differential backups available.
  

Each backup type has inherent advantages and disadvantages as follows:

• Full backup is the simplest backup and restore method because it gives you a single backup set to restore.
  
• The copy backup does not remove the log files. Log files must be removed or the log file drive will eventually fill up, and your Exchange database will be taken offline until the log files are purged.
  
• Differential and incremental backups can both require multiple backup sets to perform a full restore. If any of those backup sets are missing or not restorable, recovery will be to the point prior to the non-recoverable backup set. As their category type suggests, differential and incremental backups save only the changes. Because only the changes are saved, the size of backup files is smaller than a complete backup and backup takes less time.
  

Exchange 2007 supports the following methods of backing up and restoring to the active copy of the database or recovery storage group:

• Legacy streaming backup   All four types of Exchange backups (full, copy, incremental, and differential) are supported on the active copy of the database. Backups can be selected at the database level, but there can be only one backup job running against a specific storage group. Separate storage groups can be backed up at the same time.
  
• Legacy streaming restore    All four types of Exchange backups can be restored to the active copy of the database or to the recovery storage group. For detailed steps about how to restore a streaming backup to an alternate server, see How to Restore a Streaming Backup to a Different Server.
  
• VSS backup   All four types of backups can be taken from the active copy. All four types can be taken from the replicated database. Backups can be selected at the storage group level. There can be only one backup job running against a specific storage group. (If a backup of a storage group is taken from a replica, you cannot initiate a backup from the active storage group until the first backup finishes.) Separate storage groups can be backed up in parallel.
  
• VSS restore   All four types of backups can be restored to the active copy. VSS backups can be restored to the same storage group, to an alternate storage group on the same or a different server, or to a non-Exchange location as supported by the Exchange 2007 Store Writer. VSS backups cannot be restored to a storage group copy location using Exchange VSS components, but they can be restored as a file-level restore from VSS backups.
  

  Note:
  Streaming and VSS backup technologies cannot be combined either during backups or restores. Legacy incremental backups cannot be taken after VSS full backups. You cannot combine a VSS differential backup with a legacy full backup at restore time.

Windows Server Backup in Windows Server 2008 no longer supports Exchange-aware backups or restores. Unlike earlier versions of Windows Backup, you cannot make or restore streaming backups of Exchange by using Windows Server Backup. To back up and restore Exchange 2007 SP1 on Windows Server 2008, you must use an Exchange-aware application that supports the Volume Shadow Copy Service (VSS) writer for Exchange 2007, such as Microsoft System Center Data Protection Manager, a third-party Exchange-aware VSS-based application, or a third-party Exchange-aware application that uses the streaming backup APIs locally on the Exchange server to make a backup locally on the Exchange server. An application that uses a backup agent that runs locally on the Exchange server and streams the backup remotely to a backup application is considered a local backup.