Specifications

18 CHAPTER 1 SQL Server 2008 R2 Editions and Enhancements
Side-by-Side Migration
The term side-by-side migration describes the deployment of a brand-new SQL Server 2008
R2 instance alongside a legacy SQL Server instance. When the SQL Server 2008 R2 installation
is complete, a DBA migrates data from the legacy SQL Server database platform to the new
SQL Server 2008 R2 database platform. Side-by-side migration is depicted in Figure 1-6.
NOTE It is possible to conduct a side-by-side migration to SQL Server 2008 R2 by using
the same server. You can also use the side-by-side method to upgrade to SQL Server 2008
on a single server.
Data is migrated
from
SQL Server 2005
on Server 1
to
SQL Server 2008 R2
on Server 2
Migration
Pre-migration
Post-migration
Server 1
SQL Server 2005
Server 1
SQL Server 2005
Server 2
SQL Server 2008 R2
FIGURE 1-6 Side-by-side migration from SQL Server 2005 to SQL Server 2008 R2
Side-by-Side Migration Pros and Cons
The biggest benet of a side-by-side migration over an in-place upgrade is the opportunity
to build out a new database infrastructure on SQL Server 2008 R2 and avoid potential migra-
tion issues with an in-place upgrade. The side-by-side migration also provides more granular
control over the upgrade process because it is possible to migrate databases and components
independent of one another. The legacy instance remains online during the migration pro-
cess. All of these advantages result in a more powerful server. Moreover, when two instances
are running in parallel, additional testing and verication can be conducted, and rollback is
easy if a problem arises during the migration.