The use of DAGs in Exchange Server 2010 mostly
eliminates the need to perform backups of the Exchange servers because
the data is already replicated to multiple locations. The individual
identity of the mailbox, Client Access, Hub Transport, and
Unified Messenger servers becomes much less important because there is
no “unique” data store on them. This said, it is necessary to realize
that not all environments will be large enough to justify the use of
DAGs to provide protection against system failures. Smaller deployments
will still need to be backed up to allow for recovery of failed systems.
The Windows Server
2008 operating system and the Exchange Server 2010 messaging system
contain several features to enhance operating system stability, provide
data and service redundancy, and deliver feature-rich client services.
Windows Server 2008 continues to provide additional services such as
Volume Shadow Copy Service, or VSS, which works to enhance backup
capabilities when organizations use third-party backup products.
Though other options
have been mentioned, this section discusses ways to back up a Windows
Server 2008 system, including key components of Exchange Server 2010.
Because there are no built-in backup utilities available with the
Windows Server 2008 operating system that are compatible with Exchange
Server 2010, it is necessary to utilize a third-party backup utility.
By preparing for a
complete server failure and using the information in this section, an
organization is more likely to successfully recover from a failed
server, restoring it to its previous state.
Backing Up Boot and System Volumes
A backup strategy
for every nonredundant Exchange Server 2010 system should always include
the boot and system disk volumes of the server. For most Exchange
server installations, the boot and system volume are the same, but in
some designs they are located on completely separate volumes—as usually
is the case for dual-boot computers. For the rest of this section and
discussion, assume that they are both on the same partition. This volume
contains all the files necessary to start the core operating system. It
should be backed up before and after a change, such as the application
of service packs, is made to the operating system and once every 24
hours, if possible.
When Exchange Server is
installed on a Windows 2008 server, the installation, by default,
installs on the system partition unless a different location is
specified during installation. On average, the amount of information
stored on the system volume, with applications, services, and all
service packs installed, is typically approximately 15GB.
Note
When system volumes
are backed up, the System State should also be included in the backup at
the same time to simplify recovery and restoration of the system to its
original state, if a server needs to be recovered from scratch.
Backing Up Windows Server 2008 Services
Many
Windows Server 2008 services store configuration and status data in
separate files or databases located in various locations on the system
volume. If the service is native to Windows Server 2008, performing a
complete server backup on all drives and the System State almost
certainly backs up the critical data. A few services provide alternative
backup and restore options. The classic NTBackup utility has been
replaced in Windows Server 2008 with the new Windows Server Backup that
is installed as a feature. Although this utility is incapable of backing
up Exchange Server 2010, it is also capable of backing up Windows 2008.
Backing Up the System State
The System State of a
Windows Server 2008 system contains, at a minimum, the system Registry,
boot files, and the COM+ class registration database. Backing up the
System State creates a point-in-time backup that can be used to restore a
server to a previous working state. Having a copy of the System State
is essential if a server restore is necessary.
How the server is
configured determines what will be contained in the System State, other
than the three items listed previously. On a domain controller, the
System State also contains the Active Directory database and the SYSVOL
share. On a cluster, it contains the cluster quorum data. When services
such as Certificate Services and Internet Information Services, which
contain their own service-specific data, are installed, these databases
are not listed separately but are backed up with the System State.
Even though the
System State contains many subcomponents, using the programs included
with Windows Server 2008, the entire system can be backed up only as a
whole. When recovery is necessary, however, there are several different
options.
The system should be
backed up every week to prepare for several server-related failures. A
restore of a system backup is powerful and can return a system to a
previous working state if a change needs to be rolled back or if the
operating system needs to be restored from scratch after a complete
server failure.
Volume Shadow Copy Service and Exchange Server 2010
Before discussing
the backup process using Windows Server Backup, it is important for
Exchange Server administrators to understand what Windows 2008 Volume
Show Copy Service is used for. With limited native support for backing
up Exchange Server 2010, most organizations use third-party backup
products. Backup products for Exchange Server 2010 must utilize VSS
because legacy style “streaming” backups are no longer supported.
The Volume Shadow Copy
Service is a server service in Windows 2008 and is available as part of
the operating system. Alone, VSS is a service, but when combined with
backup applications, VSS become a vital part of every organization’s
backup strategy and recovery plan.
What Role VSS Plays in Backup
Microsoft created
VSS to provide application platforms and infrastructures to enhance
functionality when working with Microsoft services such as Exchange
Server 2010. The key to VSS is its capability to act as a go-between or
coordinator for service providers (backup applications) and service
writers (Exchange Server 2010 databases).
It is important to know
that VSS does not function alone; VSS is designed to provide application
developers a platform in which to build applications to create Exchange
Server snapshots.
Shadow Copies and Snapshots
This capability
enabled third-party backup applications to create shadow copies or
mirrors of the Exchange Server database and enabled administrators to
design more dynamic backup strategies and reduce the overall cost of
restoring servers. Using Shadow Copies (Mirror Copies) and Snapshots
(Point in Time Mirror Copies), daily backups can be much smaller and for
vital messaging systems, and snapshots can be taken several times a
day.
VSS Requirements and Prerequisites
When looking at
third-party products as an option for backups with VSS technology, you
must evaluate the products to ensure that they are compatible with VSS.
Compatibility is based on three specific areas:
Backups of the
Exchange Server 2010 database, logs, and checkpoint files must be
completed by the application writer (Exchange Server 2010).
The application must complete a full validation of the backup.
When restoring data in Exchange Server, this must also be completed by the application writer (Exchange Server 2010).
VSS and
third-party applications also require hardware compatibility. This is
especially true when backing up to disk subsystems, such as NAS and SAN
solutions. To verify this information, review the application vendor
support pages and verify that the application and hardware meet all
requirements.
