Datasheet

Licensing
Every DBA has probably received a dreaded licensing question or two, and we hope to answer some of
those common questions in this section. There are several ways to license SQL Server, and we can’t
address this ever-changing landscape completely in this book. Instead, we’ve tried to answer common
questions that are not as likely to change from year to year. If you were to purchase any of the licenses
we refer to in this section, they are compatible with previous releases of SQL Server as well as SQL
Server 2005.
The Server plus User Client Access License (CAL) licensing model works well if you can trace each con-
nection to a user and if you have a low number of connections to your SQL Server services. This license
licenses the server and each named user connecting to SQL Server.
The Server plus Device CAL licensing model works well if you expect that a moderate number of named
devices will connect to your instance. In this model, you license the server and then each device (a kiosk
or desktop, for example) connecting to the services of SQL Server. If you have multiple users using a sin-
gle desktop, you need only a single device CAL.
The Processor licensing model works well if you expect to have a high number of connections on your
SQL Server or if you can’t identify connections, such as an Internet application exposed to others outside
your company. This model licenses each physical or virtual processor available to the server. If you were
to disable a processor to the operating system and in turn SQL Server, this processor would not have to
be licensed. Once the available processors are licensed, you can have unlimited connections to the server.
Modern Processor Issues
In 2005, Microsoft clarified its licensing stance on multiprocessor systems. Hyperthreading allows a sin-
gle processor to simulate multiple processors. If you had a four-processor server, you would actually see
eight processors in Task Manager. With SQL Server, if you were licensing per processor, you would only
have to license the physical chip connected to the mainframe and would not be charged for the hyper-
threaded processors. This also applies in a multicore server. In a multicore machine, you would have one
physical chip connected to the mainframe that had multiple processors sitting on it. It’s essentially a pro-
cessor hub. You are charged only for a single chip versus each processor on the chip.
Scaling and High Availability Licensing Issues
As we mentioned earlier, you are only charged for the physical chips on the machine if you choose the
per-processor model. If you have 10 instances of SQL Server on a single server, you’re not charged for
each instance in a per-processor model. Another common question is with clusters. In an active-passive
cluster, you are only charged for the active server, and the passive server is at no charge. In an active-
active cluster, you are charged for each active node, so you might be charged for each node.
Oftentimes, DBAs decide to scale out SSRS, SSIS, or SSAS to avoid slowing down the relational engine.
If you were to scale one of the SQL Server BI products off of the SQL Server machine, you would need to
license the other server even though SQL Server may not be installed on it.
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