2. Preparing for
Coexistence and Migration
As it is not possible to
directly upgrade a server running Exchange Server 2003 or Exchange
Server 2007 to Exchange Server 2010, it is necessary to plan for a
period of coexistence between the two different versions of the
messaging system. This period of coexistence will allow the migration of
organizational resources from servers running the previous version of
Exchange to Exchange Server 2010. Exchange Server 2010 supports
coexistence with Exchange Server 2003, Exchange Server 2007, and mixed
Exchange Server 2003 and Exchange Server 2007 environments. Exchange
Server 2010 does not support coexistence with Exchange 2000 Server
organizations. To migrate from Exchange 2000 to Exchange Server 2010,
you must first migrate to either an Exchange Server 2003 or an Exchange
Server 2007 organization.
Note:
UPGRADE AND MIGRATION
TERMINOLOGY
In the exam objectives,
“migration” in this sense means moving from one Exchange version to
another. In the exam objectives, the term “upgrade” implies a direct
in-place upgrade, which is not possible. In the Exchange documentation,
the term “migration” is used only to discuss moving from a foreign
messaging system to Exchange or from Exchange to a foreign messaging
system. In the Exchange documentation, “upgrade” is used when moving
data from one server, such as an Exchange Server 2007 mailbox server to
an Exchange Server 2010 mailbox server. In the exam, the context is
explained, and you should remember that you cannot directly upgrade a
server running one version of Exchange to another.
2.1. Preparing an
Exchange Server 2003 Environment for Exchange 2010
If your organization
has an existing Exchange Server 2003 deployment, you must run the Setup /PrepareLegacyExchangePermissions command prior to running the Setup /PrepareSchema
command. Running this command ensures that the Exchange 2003 Recipient Update Service will function correctly after you
update the Active Directory schema using the Setup /PrepareSchema command.
There are two ways to run Setup /PrepareLegacyExchangePermissions. If you run the command without any additional
options, all domains in the forest are prepared for Exchange Server
2010. As an alternative, you can run the command in each domain in the
forest, though you need to ensure that you run the command in the domain
that holds the server that holds the schema master role first.
The user account that runs the
command Setup
/PrepareLegacyExchangePermissions with
the target, as all domains in the forest must be a member of the
Enterprise Admins group. If the command is being run for a specific
domain, the account used to run the command must be a member of the
Domain Admins group and must have been delegated the Exchange Full
Administrator permissions in the existing Exchange Server 2003
infrastructure.
Note:
PREPARE LEGACY EXCHANGE
PERMISSIONS
To learn more about preparing
legacy exchange permissions in an Exchange Server 2003 organization
prior to the deployment of Exchange Server 2010, consult the following
document on TechNet: http://technet.microsoft.com/en-us/library/aa997914.aspx.
When preparing for coexistence
between Exchange Server 2003 and Exchange Server 2010, consider the
following:
Exchange Server
2010 can coexist with an Exchange Server 2003 organization only if that
organization is configured to use Native rather than Mixed mode. An
Exchange Server 2003 organization in Mixed mode will need to be
converted to Native mode before Exchange Server 2010 can be introduced.
Existing Exchange Server
2003 servers have Service Pack 2 installed prior to beginning Exchange
Server 2010 deployment.
Introduce servers
in Internet-facing sites first.
Deploy Exchange Server 2010 roles in the
following order: Client Access, Hub Transport, Mailbox, and Unified
Messaging. You can also choose to deploy a typical Exchange Server 2010
installation where you deploy these roles at the same time.
If the existing Exchange 2003
organization contains more than one routing group and you are intending
to configure more than one routing group connector between Exchange 2003
routing groups and Exchange 2010, you will need to configure Exchange
Server 2003 to suppress link state updates. You perform this procedure
by using the Registry Editor to modify the registry on each Exchange
Server 2003 server in the organization.
Note:
EXCHANGE 2003 AND
EXCHANGE 2010 COEXISTENCE
To learn more about
deploying Exchange Server 2010 in an environment that has an existing
Exchange Server 2003 deployment, consult the following TechNet document:
http://technet.microsoft.com/en-us/library/aa998186.aspx.
Note:
SUPPRESS
LINK STATE UPDATES
To learn more about
configuring suppression of Link State updates, consult the following
article on TechNet: http://technet.microsoft.com/en-us/library/aa996728.aspx.
2.2. Preparing
Exchange 2007 Coexistence
Preparing for
coexistence between Exchange Server 2007 and Exchange Server 2010 is
simpler than preparing for coexistence with Exchange Server 2003. When
preparing for coexistence between Exchange Server 2007 and Exchange
Server 2010, consider the following:
It is not necessary to
run Setup /PrepareLegacyExchangePermissions when preparing to deploy Exchange Server
2010 in an existing Exchange Server 2007 organization.
You do need to upgrade all
servers running Exchange Server 2007 to Exchange Server 2007 Service
Pack 2 before coexistence with Exchange Server 2010 is possible.
You should deploy the first
Exchange Server 2010 servers in Internet-facing Active Directory sites.
This is because Client Access proxying works from Exchange Server 2010
Client Access servers to Exchange Server 2007 Client Access servers but
does not work in the opposite direction.
You should deploy Exchange Server 2010 roles in the
following order: Client Access, Hub Transport, Mailbox, and Unified
Messaging. You can also choose to deploy a typical Exchange Server 2010
installation where you deploy these roles at the same time.
Note:
EXCHANGE 2007 AND
EXCHANGE 2010 COEXISTENCE
To learn more about deploying
Exchange Server 2010 in an environment that has an existing Exchange
Server 2007 deployment, consult the following TechNet document: http://technet.microsoft.com/en-us/library/dd638158.aspx.
Note:
ACTIVE DIRECTORY
PREPARATION
Know the order in which you
must use the Setup /PrepareSchema, Setup /PrepareAD, and Setup /PrepareDomain
commands. Know the circumstances under which you must use the Setup /PrepareLegacyExchangePermissions
command.
