Applies to: Exchange Server 2007 SP3, Exchange Server
2007 SP2, Exchange Server 2007 SP1, Exchange Server 2007
Topic Last Modified: 2009-05-19
Microsoft Exchange Server 2007 end-user data is stored in the mailbox and public folder databases on Mailbox servers. In transit, data is stored in the transport queue databases. Transport data is transient, and there is no need to back up the queue database. Mailbox and public folder databases need to be protected by point-in-time backups. Independent of your end-to-end recovery strategy, mailbox and public folder databases must be protected with backups because they contain the only data in the Exchange deployment that cannot be re-created. These databases are protected against data loss using backups. A backup provides a point-in-time copy of the data that can be restored to a server at a later time.
|Local continuous replication (LCR), cluster continuous replication (CCR) and standby continuous replication (SCR) provide a level of protection for mailbox data. However, LCR, CCR and SCR are not replacements for regular database backups. LCR, CCR and SCR copies are near-time copies of a production database. They are continuously updated and used for fast recovery purposes. Backups are static point-in-time copies of a database that can be used to recover a database to a past point in time. SCR does include a built-in delay for log replay that also enables you to activate a database in a past point in time, but SCR is not a replacement for regular backups.|
Methods for Database Backup
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. Exchange 2007 Service Pack 2 (SP2)
includes a new plug-in that enables you to make Volume
Shadow Copy Service (VSS)-based backups of Exchange data using
Windows Server Backup in Windows Server 2008. You can use
Windows Server Backup to back up and restore your
Exchange 2007 SP2 databases. A thorough understanding of what
needs to be backed up, where to store backups, and how to restore
backups is key to being an effective Exchange administrator. For
more information about what needs to be backed up in
Exchange 2007, see Using Windows Server
Backup to Back Up and Restore Exchange Data.
For more information, see Exchange 2007 Data Backup and Volume Shadow Copy Services.
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
- 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
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.
Supported Backup and Restore Types
Backup types are divided into the categories of complete backups and change-only backups as follows:
- 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.
- 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
- 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.
Supported Backup and Restore Methods
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
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.
Database Backup and Restore on Windows Server 2008
Windows Server Backup in Windows Server 2008 no longer supports streaming 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 Server 2007 on Windows Server 2008 using the streaming backup APIs, you must use 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.
As mentioned above, Exchange 2007 Service Pack 2 (SP2) includes a new plug-in that enables you to make Volume Shadow Copy Service (VSS)-based backups of Exchange data using Windows Server Backup in Windows Server 2008. For more information about what needs to be backed up in Exchange 2007, see Using Windows Server Backup to Back Up and Restore Exchange Data.