Professional Microsoft® SQL Server® 2008 Administration

11.7. Memory

This section looks at memory — specifically, memory on the server, including some of the issues associated with memory, the options you can use, and how they can impact the performance of the server. We'll start with a basic introduction to operating system memory, and then jump straight into the details of how to configure a server for different memory configurations.

11.7.1. Physical Memory

Physical memory is the RAM you install into the server. You are probably already familiar with the SIMMs and DIMMs that go into desktop PCs and servers. This is the physical memory, or RAM. This memory is measured in megabytes, gigabytes, or, if you are lucky, terabytes, as the latest editions of Windows Server 2003 Data Center Edition can now support systems with 1TB of RAM. Future editions of the operating system will increase this number as customers demand increasingly powerful systems to solve increasingly complex business problems.

11.7.2. Physical Address Space

The physical address space is the set of addresses that the processor uses to access anything on its bus. Much of this space is occupied by memory, but some parts of this address space are reserved for things such as mapping hardware buffers, and interface-specific memory areas such as video RAM. On a 32-bit processor, this is limited to a total of 4GB of addresses. On 32-bit Intel server processors with PAE, the address bus is actually 36 bits, which enables the processor to handle 64GB of addresses. You might ...