Serviceguard Extension for SAP Version B.04.02 and B.04.51 Release Notes, December 2007

Serviceguard Extension for SAP Versions B.04.02 and B.04.51 Release Notes
What’s In this Version
Chapter 1 7
Hot Standby LiveCache for HP Storageworks XP Arrays
A clustered liveCache has a master instance, that runs on the primary node of the cluster
during normal operation. A hot standby liveCache is another liveCache instance that can be
running on the secondary node of the cluster during normal operation. The failover of the
master instance does not require any filesystem move operations or instance restarts in case a
hot standby is available. The hot standby gets promoted to become the new master. Thus, a
hot standby scenario provides extremely fast and reliable failover. The delay caused by the
failover duration is predictable and tunable. No liveCache inconsistencies can occur during
failover.
The hot standby mechanism also includes data replication. The standby maintains its own set
of liveCache data on storage at all times. SGeSAP provides a runtime library to liveCache
that allows the standby to automatically recreate outdated data via Storageworks XP
Business Copy volume pairs (pvol/svol) during startup. This utilizes fast volume copy
mechanisms within the storage array hardware. The detection of the required volumes for
replication is dynamically identified during startup of the standby. It does not require manual
maintenance steps.
The ongoing operation of the standby as well as the master failover do not require business
copy mechanisms. A storage corruption that could happen during operation of the master does
not get replicated to the logically coupled standby. The standby remains operational and can
be promoted to become the new master immediately.
The standby synchronizes the data regularly by accessing the master log files, which reside on
a CVM/CFS volume. No liveCache content data needs to be transferred via LAN. The log files
get verified online at all times, so a corruption in the logs gets detected immediately.
SGeSAP continues to support liveCache failover based on shared storage with exclusive
activation and instance restart in case a hot standby configuration is not in place.
Support for SAP MDM 5.5. Component Failover
Starting with SGeSAP version B.04.51, there is now a failover mechanism for the four server
components of SAP Master Data Management 5.5, i.e. the MDB, MDS, MDIS and MDSS
servers. They can be handled as a single package or split up into four individual packages.