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applications). SAP NetWeaver AS runs all the SAP application logic and processes, including<br />
the following examples:<br />
► SAP work dispatchers<br />
► SAP ABAP work processes<br />
► SAP Java server processes<br />
► SAP Central Services<br />
SAP NetWeaver AS also runs other SAP application logic and processes that have less<br />
impact on the planning process. Depending on the SAP application, your application server<br />
might run either ABAP processes, Java processes, or both.<br />
With SAP NetWeaver 7.0, the enqueue server and the enqueue replication, message, and<br />
gateway servers are broken out and run on a new stand-alone Central Services instance.<br />
This concept resolves the single-point-of-failure problem of the former SAP enqueue server,<br />
which then was part of the first or primary instance. For SAP installations, consider placing<br />
this central service on the z/OS platform and including it in the sysplex failover plan.<br />
The SAP project team, specifically, the SAP Basis administrator, provides basic layout and<br />
sizing documentation. The team has this information based on previous sizings to allocate<br />
budgets and procure the hardware. At this point, the hardware and operating system platform<br />
for application serving has been determined.<br />
To design your application server layout and prepare the platforms for the SAP installation:<br />
1. Review the sizing document from <strong>IBM</strong> Techline or the documentation from the team that<br />
suggested the System z hardware configuration.<br />
2. Determine the following resource requirements:<br />
– Application server processor power per application and application server<br />
The sizing output determines the processing power needed. You can distribute it<br />
across several application servers according to design and platform capacity. In most<br />
cases, the application server instance needs two processors (or cores) to permit<br />
parallelism of threads. Increasing the number of cores is not always beneficial and<br />
depends on the SAP application. The processors do not need to be physical. You can<br />
define virtual processors and thus share the physical ones with several SAP<br />
NetWeaver AS instances.<br />
– The number of application servers required per application<br />
The number depends on the selected hardware, virtualization capabilities of the<br />
platform to host several AS, and availability requirements. For production, SAP<br />
encourages the use of two application server instances per application at a minimum.<br />
– Memory (random access memory (RAM)) requirements per application server instance<br />
You can get this information from the Quick Sizer or Techline output. Allow for a<br />
generous amount of memory.<br />
– Disk storage requirements per application server<br />
The minimum storage for the application file systems is 17 GB for the primary server<br />
instance, plus 2 x RAM, or a 20-GB minimum for the swap files, plus 4.4 GB per<br />
installation media DVD. Allow sufficient space because the systems have a trend for<br />
dynamic growth.<br />
3. Determine the location of the SCS instance<br />
In the Installation - SAP NetWeaver 7.3 Systems guide (login required), SAP recommends<br />
that you run the SCS in the z/OS UNIX System Services environment of the database<br />
server hosting LPAR. You must run the SCS in an HA setup that permits SCS to<br />
Appendix B. Planning, preparing, and implementing the SAP landscape 155
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