Microsoft has added a new site type, the Central Administration Site (CAS). This is a site needed for large scale deployments and is used for all administration and reporting for the hierarchy. If this type of site is deployed, it would be at the top of the hierarchy. This site type is similar to the SCCM 2007 central site. However, this site can’t have clients assigned to it and can’t process client data.
When a CAS site is deployed, a primary site must also be deployed to manage systems and users (normally in the same location as the CAS). Having a CAS also allows you to deploy additional primary sites. If a CAS site isn’t installed because you are working on a small deployment, then the first site deployed in the hierarchy is a primary site. You can’t install additional primary sites if you don’t have a CAS server. However, you can install secondary sites as child sites of the single primary site server.
A primary site in SCCM 2012 is similar to primary sites in SCCM 2007. A primary site is no longer needed as a boundary for client agent settings or security or for network bandwidth control. In SCCM 2012, instead of creating different sites to manage clients, you create different collections. You can configure custom client agent settings using collection-based targeting.
A primary site can’t be a child site of another primary site. Primary sites can only be child sites of the CAS site. SCCM 2012 has moved to a flat primary site relationship (this is due to the new database replication model). However, secondary sites can still be child sites of primary sites.
Secondary sites in SCCM 2012 provide the same functionality as in SCCM 2007. Microsoft has introduced a new technology in SCCM 2012 that provides the ability to remove secondary sites. This is the capability of distribution points to implement bandwidth throttling and scheduling.
Secondary sites can no longer be installed from the SCCM setup. They must be installed from the console. These are the available options presented by setup.
SCCM 2012 sites can now publish site data to Active Directory (AD) trusted forests for improved support to clients there. Although beta 2 supports clients in workgroups, it does not support clients in untrusted forests.
SCCM 2012 no longer uses mixed or native site modes. Instead, it supports multiple management points on the same site, where a management point can be configured to support secured HTTPS client communication using PKI, and other management points can be configured to support unsecured HTTP communication. Load balancing a management point using Network Load Balancing (NLB) is no longer needed.
Microsoft does not support performing an in-place upgrade from SCCM 2007 to SCCM 2012. To upgrade, you must perform a side-by-side migration. This is due to SCCM 2012 now being a native 64-bit application and changes in site types and site relationships.
In SCCM 2012, you can’t change the parent relationship of an active site. You can make a site a child of another one only when installing it as a new site. This is due to the new database replication model.