Often, for simplicity’s sake, developers and IT staff like to put one application on one server. This enables people to say things like, “That’s the database server.” Sometimes there are good reasons for the one application, one server rule. Often, there is no real reason, and several applications could live quite efficiently together. Consequently, consolidating applications, usually along with the data, is (or should be) part of the server consolidation process.
This is not necessarily easy. Reconfiguring applications and data requires great attention to detail. Security, access rights, performance, storage management, and maintenance are just some of the issues that must be resolved. To give you a flavor of the subtleties in server consolidation, consider licensing. Common sense says that by running fewer copies of an application there is licensing money to be saved. However, that depends on how a vendor prices its licenses. With per-seat pricing, costs will not change because the number of users will remain the same. Pricing by size or number of processors may not change much either, since consolidation typically involves fewer but larger servers. Some vendors will bargain. Whatever the situation, this is just one area of consolidation that requires thought and care.