How to make a PDC changeover without a BDC
My PDC was cutting edge—5 years ago. With time, resources that I once had in excess became bottlenecks. (I remember getting my first 500MB hard disk and thinking that I'd never use all that space.) Replacing an inadequate Windows NT PDC requires careful planning and a deliberate approach. Although my situation won't be the same as yours, understanding how I replaced my aging PDC might help you when you face a similar situation.
Prepurchase Planning
Before you decide what kind of system to purchase, you need to estimate what your PDC needs to be able to handle. My old PDC supported RAS, DHCP, WINS, directory shares, and printer shares, and I wanted my new PDC also to provide home directories. With those requirements in mind, I calculated my storage and memory needs.
I needed 5GB of hard disk space to support the storage needs of the old PDC. When predicting how much storage my growing network would demand beyond this base figure, I considered user-storage needs, system needs, and new applications (e.g., Microsoft SQL Server) I expected to add. I had collected disk-storage figures for 6 months and was able to predict how fast my PDC's storage needs were likely to grow. Historically, my storage needs have increased by about 5 percent per year. To meet these growth needs over the next 3 to 5 years, including expected program additions, I estimated I would need an additional 5GB of storage. Half of the 40 users on my network use only email. I estimated that my PDC would need another 20GB of storage to provide home directories for the remaining 20 users. I planned to configure my system and boot partitions with a generous 15GB IDE drive and set up five SCSI-based RAID 5 drives (four 5GB drives for storage and one 5GB drive for fault tolerance).
I ran Performance Monitor and analyzed the results of the memory counters to figure memory requirements for the new PDC. The results showed my old PDC's 128MB of RAM to be inadequate, so my new PDC would have 256MB of RAM. I also decided to upgrade from a 266MHz Pentium II processor to a 500MHz Pentium III processor. When you calculate your network needs, remember to consider any peripherals, such as RAS modem banks and CD-ROM towers, that you might need to upgrade or add.
Prechangeover Planning
After I ordered the hardware, I needed to decide which methods to use to move to the new PDC. Many methods require a BDC, which I didn't have. If you have a BDC or your system configuration requires you to reestablish trust relationships, replicate directories, reapply DNS, and reschedule jobs, then modify or add to the list of steps I followed.
Before I began the installation, I documented the services (including startup settings and any special accounts the services run under), programs (and their configuration settings), and network protocol settings on my old PDC. I used the Microsoft Windows NT Server 4.0 Resource Kit Sclist utility to list the services.
As I documented the old PDC's programs, I located the installation disks for these programs and copied the disks to a share on the old PDC. I also checked for updated drivers on vendor Web sites and copied to the share all the drivers I would need. In addition, I used the network protocol documentation to compare each server's protocols and bindings between protocols and services.
Making the Move
I let the users know that the domain would be down temporarily, and I did the job on a weekend night so that the transition would affect as few users as possible. Before I made the move, I backed up my old PDC and did a partial restore to ensure that the backup was reliable.
Step 1
Install the new PDC as a BDC. When I installed NT Server 4.0 on the new server, I chose the option to install the server as a BDC and gave the new server the name NEWPDC. I also installed all the protocols that the old PDC was running.
If your new PDC has NT Server preinstalled, you'll need to reinstall the OS to add the new server to your domain as a domain controller (DC) and recreate the domain SID. Consider requesting that the OS be preinstalled as a member server. You then can use Algin Technology's UPromote to add the server to the domain as a BDC without reinstalling the OS.
Step 2
Install services. I referred to the documentation I compiled in preparation for my PDC changeover and installed the services my new PDC would need, such as WINS and RAS. I also installed Service Pack 6a (SP6a) and used Control Panel to verify the installations.
If you want to run any services under special accounts, use the Control Panel Services applet to change the services' startup configurations on the new PDC at this time. Select the service whose startup configuration you want to change, then click Startup. Enter the account and the account's password in the Log On As section.
I opened Server Manager on the new PDC and manually synchronized the domain by selecting the old PDC's name and selecting Synchronize Entire Domain from the Computer menu. This precaution ensures that the SAM databases on the old and new servers are synchronized and the protected channel between the DCs is established properly.
To compare the services now running on the two servers, I used the Sclist utility again to list services and service status information:
SCLIST -r <oldpdcname> >C:\oldservices.txt
SCLIST -r <newpdcname> >C:\newservices.txt
I compared the two lists to ensure that the services were running properly on the new PDC.
Before you proceed, determine when you want to change the name of the new server to the name the old server had. When you change the name depends on which programs you'll install on the new PDC. For example, if the new PDC runs Microsoft Exchange Server or SQL Server, set the permanent computer name now so that you don't need to make manual program configuration changes later.