Technical Requirements | Business Information Warehouse for SAP (Prima Techs SAP Book Series)

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The most time-consuming process in constructing a data warehouse is identifying the source systems, mapping data elements between source and target systems, and performing data transformation to build navigational data objects for reporting. Most of these processes are already taken care of in SAP BW if you use standard business content. Because SAP BW is based on the SAP R/3 infrastructure, you already have that in place as well. You are left with the following technical tasks for SAP BW:

Sizing
Interface with Non-R/3 Data Sources
Data Modeling
Information Delivery Infrastructure

SAP BW sizing is a very complex task. A variety of factors are important to consider when estimating hardware requirements for SAP BW. Estimating the appropriate system landscape, projecting database loads, and examining data design issues and their possible impact on system performance seem challenging-especially when these considerations impact not only the database/application server-level hardware requirements, but also the operating system, database, and application tuning requirements, as well as end-user workstations.

SAP describes BW configurations in terms of T-shirt sizes as Extra Small (XS), Small (S), Medium (M), Large (L), and Extra Large (XL). Based on present customer configurations, SAP has proposed some basic configurations for SAP BW, as shown in Table 5-1.

Table 5-1: SAP BW Hardware Configuration Model (Source: SAP)
BW Category	Configuration	Hardware	Number of Concurrent Users
XS	DB + app server (in one box)	>=1GB RAM, >=2 CPUs, DB 30-50 GB	1-10
S	DB + app server (in one box)	>= 1.5 GB RAM, 2-4 CPUs, DB 50-100 GB	10-20
M	DB and app server on separate servers	>=1.75 GB RAM, 2-4 CPUs on both servers DB 100-200 GB	20-50
L	One DB server with multiple app servers	>=2 GB RAM, DB server >= 6 CPUs, app server >=2 CPUs >=2 GB RAM DB 200-1000	50-100
XL	One DB server with multiple app servers	>=4 GB RAM, DB server >=8 CPUs, app server >= 2CPUs >= 22GB RAM DB >1000GB	>100

Consider the following factors when deciding which of the SAP-recommended configurations to use as a baseline for estimating your hardware requirements:

How much source data is going to be extracted from other systems (both R/3 and non-R/3)?
How many concurrent users will access SAP BW?
What is the query mix? How many users will be performing light (lookup, snapshot), moderate (navigation across few dimensions), or complex analyses?
What availability features, such as Redundant Array of Inexpensive Disks (RAID) and system redundancy, are required?
What is the complexity of the database design? Will many InfoCubes be required? This will help assess the total storage requirements, in addition to the query mix.
How fast is the system likely to grow in terms of users or data?

Recently, SAP has asked hardware vendors to provide systems configurations for SAP BW and OLAP benchmarks based on sales order data. These configurations will provide some reasonable system configurations on specific hardware platforms. At the time of this writing, only IBM had announced SAP BW 1.2B benchmarks on DB2. The benchmark details are available at the SAP corporate Web site, www.sap.com/BW. None of the hardware vendors had published BW 2.0x benchmarks.

Caution

SAP BW benchmarks are based on data loads using flat files not from an SAP R/3 data source. Similarly, query execution does not represent real end-user interaction. Business Explorer Analyzer is not used for query execution; rather, queries are simulated via scripts bypassing Microsoft Excel and network usage. So read these benchmarks carefully.

These benchmarks provide information on two areas: data staging and data access. The SAP BW staging process includes loading data (full and delta) in the ODS and InfoCubes and building aggregates. Database activity processes the same query in parallel with different navigation modes. According to benchmarks, the average query-response time must be less than or equal to five seconds.

SAP BW benchmarks are a good way to compare SAP BW platforms offered by several hardware vendors. Based on benchmarks, price/performance analysis, and overall operations costs, you can decide if the platform that you use for SAP R/3 operations is suitable for your SAP BW operations. In some cases, you may elect to use a different platform for SAP BW than what you use for SAP R/3 operations.

Don't forget network requirements. Because SAP BW is using a standard R/3 4.x core system, the same network requirements apply to an inter-server connection. SAP recommends a 100 Mbit connection. Nevertheless, the data traffic between the application server and the client is three to five times higher than with a standard SAPGUI (2 kbaud/user). Both LAN and WAN connections are possible and deliver high performance.

Note

Remember that SAP R/3 is a data source for SAP BW. Calculate database table growth in SAP R/3 when preparing the initial data loads for SAP BW. You also need to account for additional table space and memory needed for IDOC processing for SAP BW. Note that IDOC processing is very CPU intense. Add additional CPUs, and memory needs to be added at the application-server level. The best option is to configure one dedicated application server against SAP R/3 to process IDOCs for SAP BW. This overcomes any SAP R/3 system-resource contention problems associated with the data extractor.

For SAP BW, you need a fast end-user workstation compared to that of the typical SAP R/3 SAPGUI client. SAP suggests the following SAP BW client configurations:

Windows 95: Minimum 64MB (128MB is strongly recommended), Pentium 300MHz
Windows NT4.0/2000/98: Minimum 64MB (128MB is strongly recommended), Pentium II 300MHz

Windows NT 4.0 with 128MB of memory with fast graphics display is the ideal configuration for an SAP BW client.

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