The Big Bang approach to migrate from Windows Server
2008 to Windows Server 2008 R2 is the most straightforward approach to
migration. An upgrade simply takes any and all settings on the domain
controllers and upgrades them to Windows Server 2008 R2. If a Windows
Server 2008 server handles Windows Internet Naming Service (WINS),
domain name system (DNS), and Dynamic Host Configuration Protocol
(DHCP), the upgrade process will upgrade all WINS, DNS, and DHCP
components, as well as the base operating system. This makes this type
of migration very tempting, and it can be extremely effective, as long
as all prerequisites described in the following sections are satisfied.
The prerequisites are as
follows:
The operating system on
the domain controllers is Windows Server 2003 SP2 or higher.
The domain controller
hardware exceeds the Windows Server 2008 R2 requirements and all
software is compatible with Windows Server 2008 R2, including antivirus
software and drivers.
There is enough disk space free to perform the operating
system and Active Directory upgrade. Specifically, verify that your free
space is at least twice the size of your Active Directory database plus
the minimum 32GB needed to install the operating system.
The current domain functional
level is Windows 2000 Native or Windows Server 2003. You cannot upgrade
directly from Windows NT 4.0, Windows 2000 Mixed, or Windows Server 2003
interim domain functional levels.
Often, upgrading any given server can be a project
in itself. The standalone member servers in an environment are often the
workhorses of the network, loaded with a myriad of different
applications and critical tools. Performing an upgrade on these servers
would be simple if they were used only for file or print duties and if
their hardware systems were all up to date. Because this is not always
the case, it is important to detail the specifics of each server that is
marked for migration.
Verifying Hardware
Compatibility
It is critical to test the
hardware compatibility of any server that will be directly upgraded to
Windows Server 2008 R2. The middle of the installation process is not
the most ideal time to be notified of problems with compatibility
between older system components and the drivers required for Windows
Server 2008 R2. Subsequently, the hardware in a server should be
verified for Windows Server 2008 R2 on the manufacturer’s website or on
Microsoft’s Hardware Compatibility List (HCL), currently located at http://www.microsoft.com/whdc/hcl/default.mspx.
Microsoft suggests minimum
hardware levels on which Windows Server 2008 R2 will run, but it is
highly recommended that you install the OS on systems of a much higher
caliber because these recommendations do not take into account any
application loads, domain controller duties, and so on. The following is
a list of Microsoft’s minimum hardware levels for Windows Server 2008
R2:
1.4GHz 64-bit processor
512MB of RAM
32GB free
disk space
That said, it cannot be stressed
enough that it is almost always recommended that you exceed these levels
to provide for a robust computing environment.
Note
One of the most
important features that mission-critical servers can have is redundancy.
Putting the operating system on a mirrored array of disks, for example,
is a simple yet effective way of increasing redundancy in an
environment.
Verifying Application
Readiness
Nothing ruins a
migration process like discovering a mission-critical application that
is installed on the current Windows Server 2003 server will not work in
the new environment. Subsequently, it is very important to identify and
list all applications on a server that will be required in the new
environment. Applications that will not be used or whose functionality
is replaced in Windows Server 2008 R2 can be retired and removed from
consideration. Likewise, applications that have been verified for
Windows Server 2008 R2 can be designated as safe for upgrade. For any
other applications that might not be compatible but are necessary, you
either need to move them to another Windows Server 2003 server or delay
the upgrade of that specific server.
In addition to the
applications, the version of the operating system that will be upgraded
is an important consideration in the process. A Windows Server 2003 SP2
or R2, Standard Edition domain controller can be upgraded to either
Windows Server 2008 R2, Standard Edition or Windows Server 2008 R2,
Enterprise Edition. However, a Windows Server 2003 SP2 or R2, Enterprise
Edition installation can only be upgraded to Windows Server 2008 R2,
Enterprise Edition.
Backing Up and Creating
a Recovery Process
It is critical that a
migration does not cause more harm than good to an environment.
Subsequently, we cannot stress enough that a good backup system is
essential for quick recovery in the event of upgrade failure. Often,
especially with the in-place upgrade scenario, a full system backup
might be the only way to recover; consequently, it is very important to
detail fallback steps in the event of problems. The backup should
include the boot and system partitions as well as the System State.
Virtual Domain
Controller Rollback Option
It is always good to
have several fallback options, in case one of the options is
unsuccessful. Another option to consider, in addition to a full backup,
is to create a virtual domain controller. Using a virtual server
platform such as Hyper-V or VMware Server, you can create a domain
controller for little or no cost.
A virtual machine is created
on the host, which can be an existing installation or even on a desktop
with Virtual PC or VMware Workstation. This virtual machine is then
joined to the domain and promoted to be a domain controller.
Prior to the upgrade,
the virtual domain controller is shut down. Backup copies of the virtual
domain controller files can even be made for safekeeping.
In the event of a major failure
in the upgrade process, the virtual domain controller can be used to
rebuild the domain from scratch. If the upgrade is successful, the
virtual domain controller can either be turned back on and demoted, or
simply be deleted and cleaned from the domain.
Performing an Upgrade
on a Single Domain Controller Server
After all various
considerations regarding applications and hardware compatibility have
been thoroughly validated, a standalone server can be upgraded.
The health of the domain
controllers should be verified prior to upgrading the domain
controllers. In particular, the Domain Controller Diagnostics (DCDIAG)
utility should be run and any errors fixed before the upgrade. The
Windows Server 2003 DCDIAG utility is part of the Support
Tools, which can be found on the installation media under
\support\tools\. The Support Tools are installed via an MSI package
named SUPTOOLS.MSI in Windows Server 2003. After installing the tools,
the DCDIAG utility can be run. The same utility is included in Windows
Server 2008 with no additional installs required. Execute the tool and
verify that all tests passed.
The Active Directory
Domain Services forest and the domain need to be prepared prior to the
upgrade. This installs the schema updates that are new to Windows Server
2008 R2 Active Directory. The following steps should be run on the
Flexible Single Master Operations (FSMO) role holder(s), specifically
the schema master for forestprep and the infrastructure master for
domainprep. In a small environment or a single domain, all these roles
are typically on the same domain controller. To prepare the forest and
domain, execute the following steps on the domain controller with the
roles:
1. | Insert
the Windows Server 2008 R2 DVD into the drive. If the Install Windows
autorun page appears, close the window.
Note
When preparing the forest, be
sure to log on to the schema master as a member of the Schema,
Enterprise, and Domain Admins group.
|
2. | Select
Start, Run.
|
3. | Enter d:\support\adprep\adprep.exe
/forestprep and click OK, where d: is the DVD drive.
|
4. | A warning appears to verify that all Windows 2000
domain controllers are at Service Pack 4 or later. Enter C and
press Enter to start the forest preparation.
|
5. | Enter d:\support\adprep\adprep.exe /domainprep
/gpprep and click OK.
|
6. | Enter d:\support\adprep\adprep.exe /rodcprep
and click OK. This update allows Read-Only Domain Controllers.
|
Now that the schema updates
have been installed and the domain preparation is done, the domain is
ready to be upgraded. The FSMO role holder should be the first Windows
Server 2003/2008 domain controller to be upgraded. Follow these steps to
upgrade:
1. | Insert
the Windows Server 2008 R2 DVD into the DVD drive of the server to be
upgraded.
|
2. | The
Install Windows page should appear automatically. If not, choose Start,
Run and then type d:\Setup, where d: is the drive letter for
the DVD drive.
|
3. | Click
Install Now.
|
4. | Click the
large Go Online to Get the Latest Updates button. This ensures that the
installation has the latest information for the upgrade.
|
5. | Enter your product key and click Next.
|
6. | Select the I Accept the License Terms option on the
License page, and click Next to continue.
|
7. | Click the large Upgrade button.
|
8. | Review the compatibility report and verify that all
issues have been addressed. Click Next to continue.
|
9. | The system then copies files and reboots as a Windows
Server 2008 R2 server, continuing the upgrade process. After all files
are copied, the system is then upgraded to a fully functional install of
Windows Server 2008 R2 (see Figure 1) and will then
reboot again. All this can take some time to complete.
|
10. | After the
final reboot, the domain controller will be at the familiar
Ctrl+Alt+Del screen. After logon, the domain controller will open to the
Server Manager console, as shown in Figure 2. The domain
controller upgrade is complete.
|
The upgrade process shown in
steps 1 through 10 is then repeated for each of the remaining Windows
Server 2003/2008 domain controllers.
