SAP with Microsoft SQL Server 2005: Best Practices for High Availability, Maximum Performance, and Scalability68
64-Bit Computing Configurations
SQL Server 2005 Enterprise Edition for SAP products is supported on the 32-bit, Itanium 64 (IA64), and x64 computing platforms. For the most demanding applications, SAP 64-bit products, and Microsoft SQL Server 2005 (64-bit) and Microsoft Windows Server 2003 (64-bit) can be used to enable SAP customers to implement large-scale deployments. Large SAP workloads can be processed by using 64-bit computing because it offers a sizeable amount of memory, including SAP BW cubes and Unicode implementations.
In many organizations, SAP applications have outgrown the memory addressing capabilities of 32-bit platforms. For example, frequent out-of-memory errors can occur when running large batch jobs on two-tier SAP application servers. In this situation, increasing memory capabilities in some 32-bit SAP processes can require complicated workarounds that reduce performance.
In addition, the increased need for CPU processing power has pushed the addressing of memory to the limits of the 32-bit computing. Some organizations will need to upgrade to a 64-bit platform as 32-bit server hardware reaches the end of its life cycle.
32-Bit computing architecture
The typical 32-bit architecture limits computing power in memory-intensive processing and might produce bottlenecks and slowdowns.
Limited memory management. In 32-bit computing, a flat, 32-bit virtual address space that can be addressed to 4 GB is used. In this case, 2 GB or 3 GB are directly addressable by an application and only 2 GB are addressable by the operating system. The 32-bit virtual address space is shared across all processes, further limiting the available memory that can be addressed directly. Because each server has a limited processing capability, the 4-GB virtual address memory ceiling in 32-bit architecture can inhibit growth, degrade overall performance, and increase costs.
Limited development opportunities. Existing 32-bit architectures might not meet the demanding workloads found in a SAP environment. For example, 32-bit computing may not allow adequate amounts of RAM to perform processes in a convenient way.
64-Bit computing architecture
The use of 64-bit processors is steadily increasing because 64-bit computing:
Offers extended memory management, allowing more memory to be addressed in a linear manner.
Provides greater memory access than its 32-bit predecessors and speeds numeric calculations.
Eliminates the 4-GB memory barrier inherent with 32-bit systems, enables larger I/O buffering, and improves throughput.
Supports up to 1 terabyte of physical memory.
Offers an extensive virtual memory address space. The 64-bit architecture allows virtual memory to be addressed in a flat address space of up to 16 terabytes, divided evenly between user mode and kernel mode. This gives native 64-bit applications 8 terabytes of virtual address space.
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