For Day 16 of this series, I want to talk a little bit about the new hardware license limits that were introduced with in SQL Server 2008 R2. As you may be aware, Microsoft introduced two new high-end editions of SQL Server that are above the old “top-of-the-line” SQL Server Enterprise Edition. These are SQL Server 2008 R2 Data Center Edition and SQL Server 2008 R2 Parallel Data Warehouse

SQL Server 2008 R2 Data Center Edition is the new “top-of-the-line” edition of SQL Server 2008 R2. It allows an unlimited number of processor sockets and an unlimited amount of RAM. You are basically forced into buying Data Center Edition if you have a database server with more than eight processor sockets or (in the future), you need more than 2TB of RAM in your database server. It also allows you to have a Utility Control Point (UCP) that manages more than 25 SQL Server instances. Realistically, you would not want to manage more than about 200 SQL Server instances in a single UCP, due to resource limitations in the UCP instance.

SQL Server 2008 R2 Parallel Data Warehouse (which was code-named “Project Madison”) is a special Original Equipment Manufacturer (OEM)-only edition of SQL Server 2008 R2 that is intended for large data warehouses. This means that you cannot buy SQL Server 2008 R2 Parallel Data Warehouse by itself. Instead, you must buy it packaged with hardware from a major hardware vendor like HP. It enables SQL Server data warehouses to grow into the hundreds of terabyte range, and to be spread across multiple servers (similar to offerings from other companies, such as Teradata).

What is new for SQL Server 2008 R2 Standard Edition and SQL Server 2008 R2 Enterprise Edition, are more restrictive hardware license limits compared to the SQL Server 2008 versions of both of those editions.

SQL Server 2008 Enterprise Edition had no limit for the number of processor sockets, but was limited to 64 logical processors. SQL Server 2008 R2 Enterprise Edition imposes a new limit of eight physical processor sockets, but will theoretically let you use up to 256 logical processors (as long as you are running on Windows Server 2008 R2). However, this is not possible, currently, since it would require a processor with 32 logical cores. As of April 2011, the highest logical core count you can get in a single processor socket is 20 (if you are using the new Intel Xeon E7 series). Also, the RAM limit for R2 has changed from “operating system limit”, as it was in the 2008 release, to a hard limit of 2TB.

SQL Server 2008 R2 Standard Edition  has a new RAM limit of 64GB. This lowered limit may catch many people by surprise, since it is very easy to have much more than 64GB of RAM, even in a two-socket server. You should keep this RAM limit in mind if you are buying a new server and you know that you will be using Standard Edition. One possible workaround for this limit would be to have a second or third instance of SQL Server 2008 R2 Standard Edition installed on the same machine, so you could use more than the 64GB limit for a single instance. The physical socket limit for SQL Server 2008 R2 Standard Edition is still four processor sockets.

Make sure to keep these limits in mind if you are buying a new server that will be running SQL Server 2008 R2 (or if you are upgrading to SQL Server 2008 R2 on a large existing server, because they are different that before.