Sometimes you may find it necessary to copy the WSUS catalog and updates from a server in one site to another, or to simply copy/move the data on one server to another, and since I don't think we spell that out anywhere I thought I'd post the steps here. This is a question that always seems to come up from time to time so hopefully this will help you save some time if you're ever faced with this task:
1. Install WSUS on the import server (the server you're moving data TO).
2. Ensure that the advanced synchronization options on the export server match the settings on the import server. This means you'll have to ensure that advanced synchronization options for express installation files and languages on the export server (the server you're moving data FROM) match the settings on the import server (the server you're moving data TO).
3. Copy all of the files and folders in WSUSInstallationDrive:\WSUS\WSUSContent\ from the export server to WSUSInstallationDrive:\WSUS\WSUSContent on the import server.
Important Note: You must maintain the directory structure for all folders under \WSUSContent
4. Export the update metadata from the database on the export server using WSUSutil.exe located at the \program files\update services\tools folder.
The package (.cab file) and log file name must be unique. WSUSutil.exe creates these two files as it exports metadata from the WSUS database.
5. Move the export package you just created to the import server.
6. Import metadata to the database of the import server. At the command prompt on the import server, navigate to the directory that contains WSUSutil.exe and run the following: "wsusutil.exe import packagename logfile".
For example: wsusutil.exe import export.cab import.log WSUSutil.exe imports the metadata from the export server and creates a log file of the operation.
Note: It can take from 3 to 4 hours for the database to validate content that has just been imported.