Setting up a managed metadata service application to server one or more web applications

Found article at
http://www.lamber.info/post/2010/12/12/Setting-up-a-managed-metadata-service-application-to-server-one-or-more-web-applications.aspx

Assigning two or more managed metadata service applications to a single web application

You are also able to assign multiple service applications to a single web application. When doing so with a managed metadata service application, however, you have to consider some settings before proceeding.

Imagine that you have to maintain two separate managed metadata service applications for two different departmental projects. You can do this by creating two separate managed metadata service applications and assign them to the corresponding web applications. After a while, you need to combine both service applications for a single web application. You can do this by following the same steps as seen in the previous scenario. Choose the service applications that you want to consume in your web application by selecting a proxy group or defining your custom selections.

You can do this, however, you have to consider following when assigning multiple managed metadata service applications to a single web application:

1. both term stores (service applications) with managed terms are available for your web application
2. both term stores can provide content-type hub syndication
3. the already stored enterprise keywords of both term stores are served to your web application, however, only one term store of both can be your default storage location for your keywords
4. the already stored column specific term sets of both term stores are served to your web application, however, only one term store of both can be your default storage location of your column specific term sets

Everything except the storage of enterprise keywords and column specific term sets function properly. This happens if both managed metadata service applications are configured to be the default term stores. You might encounter following error message when inserting a new enterprise keyword:

Therefore, plan carefully before separating managed metadata service applications. You have to ensure that only one of both term stores is the default term store for the web application. You can make the changes in the managed metadata service connection settings:

• open the central administration
• Application management –> Manage service applications
• select the row of type Managed Metadata service Connectionof your metadata service application
• press Properties in the ribbon bar
• choose This service application is the default storage location for Keywords and This service application is the default storage location for column specific term sets

If you already have a default term store in the farm you will get this error message:

Now, it is up to you to ensure that you do not use two default term stores on the same web application. Please note that disabling these settings is a farm wide setting.