SAP with Microsoft SQL Server 2005: Best Practices for High Availability, Maximum Performance, and Scalability25
SAP Connections to SQL Server
With SQL Server 2005, multiple open client-side cursors can use one connection such as Multiple Active Result Sets (MARS). In contrast to earlier SQL Server releases, the number of connections of a SAP process to SQL Server 2005 is limited to two connections for each SAP process as shown in Figure 10.
SAP executes “dirty” reads. In order to scale, SAP reads most of the data on an uncommitted read isolation level. This is done on one of the two connections.
All data modifications, plus some reads requiring read-committed isolation, are handled on the other SAP connection.
Security context of SAP transactions
mySAP benefits from SQL Server 2005 integrated security for strong, trustworthy installations. The security context of SAP transactions is established during the installation of SAP NetWeaver Application Server:
SAP creates two Windows users named SAPService<SID>, for example, SAPServicePRD and <SID>adm such as PRDadm. The <SID> represents the three-character SAP System ID.
Windows users are created as logins. In SQL Server 2005, two Windows users log in by using Windows Authentication. SAP recommends installing SQL Server 2005 integrated security to accept connections only. For SAP databases, these two logins are assigned to the SQL Server system administrator (sa) role and the dbo database role.
A SQL Server login is created for each user owning a schema in the SAP database. A login cannot be performed interactively because SQL Server only accepts integrated security connection attempts. Each user is assigned to the SQL Server serveradmin fixed server role. Each user owning a schema in the SAP database is assigned to the dbo database role.
Microsoft Corporation © 2005