Sometimes happens that we may install both the Reporting Services Windows service and the Report Catalog on the same server (Not Best Practice). However, some organizations may choose to place these items on separate servers. This can be done through either a distributed installation or a scale-out installation.
In a distributed installation, the Reporting Services items discussed here are not installed on a single server. Instead, they are split between two servers that work together to create a complete Reporting Services system. One server runs SQL Server database engine and hosts the databases that make up the Report Catalog. This is the database server. The other server runs the Reporting Services Windows service. This is the report server.
The following figure shows a distributed installation.
The distributed installation has advantages when it comes to scalability. Because the workload of the Reporting Services Windows service and the SQL Server database engine is divided between two servers, a distributed installation can serve reports to a larger number of simultaneous users. The disadvantage of this type of installation is that it is more complex to install and administer. However, if we need a high-volume solution, it is certainly worth the effort to obtain a solution that can provide satisfactory response times under a heavy workload.
The scale-out installation is a specialized form of the distributed installation, In a scale-out installation, a single database server interacts with several report servers. Each of the report servers uses the same set of Report Catalog databases for its information. By using additional report servers, we can handle even more simultaneous users with the scale-out installation than we could with the distributed installation. When Report Designers create reports, they can deploy them to any of the report servers. No matter which server is used, the reports end up in the single Report Catalog. Once the reports are in the Report Catalog, they can be delivered by any of the report servers. In addition, because all information about the Report Manager is stored in the Report Catalog, any changes to the Report Manager made on one server take effect on all the servers.
As with the distributed installation, the scale-out installation provides a way to handle a large number of simultaneous requests for reports. Even though the scale-out installation uses a number of servers to deliver reports, it allows the Report Manager interface to be administered without duplication of effort. The scale-out installation may take additional effort to get up and running, but once it is ready to go, it provides an efficient means of serving a large number of users.