In Windows NT 4.0, the domain controller (DC) promotion and demotion process requires a complete rebuild of the server. You can turn a server into a DC only during Windows setup. This situation presents a problem to administrators who want to change the role of a server while retaining other shared services, and rebuilding a system from scratch isn't exactly an attractive prospect. Windows 2000 Server improves on the NT 4.0 DC promotion and demotion process by permitting an administrator to use the Dcpromo utility to promote a standalone or member server to a DC. A demotion is also a simple Dcpromo task, assuming you have connectivity to a healthy, functional DC within the domain.
However, even in the improved Win2K Dcpromo process (pre—Service Pack 4—SP4), a problem lingers: To perform clean demotions, Win2K Dcpromo requires the DC to have physical network connectivity to another functioning DC. Other stumbling blocks, such as corrupt objects in the directory, can also lead to demotion problems. If a clean demotion is impossible, you're looking at a complete rebuild of the server, as well as a metadata cleanup, to remove the DC from the directory. Another promotion limitation that's been around since the early days of NT is the requirement of replicating all data over the network—you've never been able to perform a promotion from a compressed file or storage medium shipped to a remote location. With pre—Active Directory (AD) domains, such replication wasn't a huge problem, given the size limitations of the SAM databases in those versions. With AD, one Directory Information Tree (DIT) file can be 10GB or larger. In large environments that use Win2K AD, promoting a Global Catalog (GC) server in the far reaches of the network can take as long as 4 to 5 days.
Vastly improving on Win2K Server's promotion and demotion process, Windows Server 2003's Dcpromo lets you force a demotion regardless of connectivity to the domain and regardless of the status of objects relating to the DC. (The Dcpromo version in Win2K SP4 also permits forced demotions.) But arguably the most popular feature of Windows 2003 Dcpromo is its ability to promote a DC from media. The medium necessary to promote a DC is essentially a directed restore of a system state backup from another Windows 2003 DC. This backup medium lets you promote DCs in remote locations in far less time than Win2K requires. By using Windows 2003 Dcpromo to promote a DC from media, you can promote the same GC that took 4 to 5 days with Win2K in a matter of minutes, depending on the age of the system state backup you use. These added features will not only save you hours of wasted time rebuilding servers from scratch but also open up the door to new methods of disaster recovery and deployment.
Dcpromo from Media
Windows 2003 Dcpromo's new ability to promote from media can greatly improve your ability to recover from DC failures, particularly in remote sites where repromoting a DC over the wire can take hours or even days, depending on WAN bandwidth and the size of your directory. The feature can also dramatically speed your ability to roll out AD services to remote sites as well as decrease the amount of WAN traffic necessary to promote DCs. You can use this process to create only replica DC or GC servers, and both systems should have the same level of OS patches. Promoting a DC from media requires that you first ensure the following:
- The system state backup must be no more than 60 days old, which is the default tombstone lifetime. (Tombstone lifetime is the length of time that deleted objects remain before the DC permanently removes them from the directory. Promoting from a backup that's older than the tombstone lifetime results in the reintroduction of tombstoned objects.)
- The system state backup must be taken from a Windows 2003 DC in the same domain. If you want the DC to also be a GC server, you need to create the system state backup from an existing DC that's also a GC in the same domain.
- The source DC must be completely healthy at the time of the backup. Use netdiag.exe and dcdiag.exe to ensure that the DC has clean event logs and correct DNS registrations. Use the repadmin.exe /showrepl /all command to ensure that clean replication is occurring. Test with dummy files to make sure that you have clean File Replication Service (FRS) replication. Ensure that the DC is responsive to Lightweight Directory Access Protocol (LDAP) queries and remote procedure calls (RPCs). Make sure the DC has Netlogon and Sysvol shares. Finally, ensure that the DIT contains little fragmentation.
- The server you want to promote from media must be on the network and must be able to communicate with other healthy DCs.
The Basic Steps
You first need to use NTBackup to perform a system state backup of a healthy DC (and optionally GC), as Figure 1 shows. To do so, start NTBackup and click Advanced Mode on the first screen. On the next screen, go to the Backup tab and select the System State check box. As a best practice, consider a naming convention for the backup file that conveys the name of the source server, the date of the backup, whether the server is a GC, and the OS build number. After you type the pathname, click Start Backup. On the next screen, you can select advanced options. Clear the Automatically back up system protected files with the system state check box because those files aren't necessary for using Dcpromo from media. When the backup has completed, be sure to view the report to ensure that the backup didn't fail on any crucial files. If a failure occurred, remove any file locks and rerun the backup. (If the NT File Replication System—NTFRS—service is running, you can expect a DO_NOT_REMOVE_NtFrs_PreInstall_Directory error. You can safely ignore this error. NTFRS uses this directory, which isn't intended to be backed up.)
After you obtain the backup file, you might want to use your favorite file-compression program to compress it. By doing so, you minimize the amount of data you need to copy to the destination server you want to promote. However, some compression utilities won't compress files larger than 4GB. If you plan to use compression frequently, investigate whether your compression utility meets your needs. Copy the compressed file to the new server and expand the backup file.
Prev. page
[1]
2
3
next page 
