Managing Serviceguard Extension for SAP, December 2007

SAP Supply Chain Management
Chapter 4 201
4 SAP Supply Chain Management
Within SAP Supply Chain Management (SCM) scenarios two main
technical components have to be distinguished: the APO System and the
liveCache. An APO System is based on SAP Application Server
technology. Thus, ci, db, dbci, d and sapnfs packages may be
implemented for APO. These APO packages are set up similar to
Netweaver packages. There is only one difference. APO needs access to
liveCache client libraries. These files usually are searched via the path
/sapdb/programs. How access to the client libs is ensured depends on
the setup of the liveCache and is discussed in combination with the
liveCache volume group layout below.
The second technical SCM component, called liveCache, is an in-memory
database. The technical realization of liveCache is based on SAPDB
technology. Even though liveCache is somewhat similar to the SAP
owned database technologies, it needs special treatment. This is because
a liveCache Instance usually is closely coupled with the accompanying
APO. SAP has defined a list of policies and requirements to failover
solutions in order to allow support for liveCache High Availability.
Table 4-1 Supported SGeSAP lc package types
Master Token Failover with
hot standby system (hss)
Instance Failover and Restart
Use this solution for those more
demanding environments that
require failover times in the
minute range, regardless of the
size of the liveCache database.
Use this solution for small
liveCache databases, where the
liveCache restart times during
failover satisfies the service level
that the business need dictates.
Take into account that you may
temporarily see a significant
performance degradation as the
liveCache is restarted.