Under certain circumstances, the STSADM MergeContentDBs command may fail in Windows SharePoint Services 3.0. These circumstances include combinations of significant site collection size, user traffic, and SQL Server load. When the STSADM MergeContentDBs command fails, both the source and destination databases can be corrupted.
This issue may occur when you use the STSADM MergeContentDBs command on a Site Collection that is larger than 10 gigabytes (GB).
To work around this problem, take the following actions when you use the STSADM MergeContentDBs command:
Always back up the source and target databases before you use the STSADM MergeContentDBs command.
Refrain from canceling the operation on the front-end Web server or on the server that is running SQL Server.
Run the STSADM MergeContentDBs command during off-peak hours because the STSADM MergeContentDBs command places significant additional load on the server that is running SQL Server.
Or, consider using Batch Site Manager and the method that is described in the "Move site collections" topic on Microsoft TechNet. To do this, visit following Microsoft Web site:
Because the Batch Site Manager works with site collections by using the STSADM backup and restore operations with the –url parameter, we recommend that you not use Batch Site Manager for site collections that are larger than 15 GB.
The Batch Site Manager is included in the SharePoint Administration Toolkit:
The workaround in this KB Article is for SharePoint deployments running the pre-April Cumulative Updates or hotfix packages. The issues in this KB Article do not apply to Servers which have been patched with the April Cumulative update or Hotfix package and later. To obtain the fix: Description of the Windows SharePoint Services 3.0 hotfix package (Sts.msp): April 28, 2009:http://support.microsoft.com/kb/968857 Description of the Windows SharePoint Services 3.0 cumulative update package: April 30, 2009:http://support.microsoft.com/kb/968850 Description of the Microsoft Office SharePoint Server 2007 hotfix package (Coreserver.msp): April 28, 2009: http://support.microsoft.com/kb/968859
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.