Ensuring a rapidly available SAP landscape involves the eliminations of all possible points of failure within the environment. A failure in system availability is very costly and hampers the productivity of the organization. Hence monitoring measures are set in place and alerts notifications are configured to be sent out to responsible operators for any possible threats caused by but not limited to:
◉ Power Failure
◉ Hardware Failure
◉ Network Latency
◉ Data Centers
The sole purpose of Implementing a High Availability SAP HANA system is to ensure a smooth and time effective recovery strategy from any failures. A fully automated High availability system is a combination of the following:
◉ SLE High Availability
◉ The HA extension is included in the SUSE Linux Enterprise server for SAP Applications 15 SP1
◉ SAP HANA Native fault tolerance features
◉ Service auto-restart occurs when a service automatically restarts itself after a local software failure. In a cluster environment SAP recommend failing SAP HANA over to a node with SAP HANA active on it as the recovery time is much faster.
Source: Richard Mayne, Training Architect at SUSE,2021
Course Title: Need SAP HANA Running 24/7? Challenge Accepted!
Figure 1: Service Auto-Restart
◉ SAP HANA auto-restart occurs usually after a power failure when a system hosting SAP HANA is started, Automatically SAP HANA will perform a start-up and recovery.
Source: Richard Mayne, Training Architect at SUSE,2021
Course Title: Need SAP HANA Running 24/7? Challenge Accepted!
Figure 2: SAP HANA Auto-Restart
◉ Host auto-failover occurs usually when a host is automatically failed over to a new active host without any human interference. The described feature is available only in a Scale out configuration setup
◉ SAP HANA system replication is a reliable high availability and disaster recovery solutions that provides continuous synchronization of a HANA database to a secondary location either in the same data center or remote site.
Source: Richard Mayne, Training Architect at SUSE,2021
Course Title: Need SAP HANA Running 24/7? Challenge Accepted!
Figure 3: SAP HANA System Replication
◉ Fault tolerant hardware components The above-mentioned features help with reducing the time to recover from a failure. The provided SAP HANA Native fault tolerance features are not enough for a fully automated HA solution for SAP HANA. Specialized components provided by SLES for SAP applications are required e.g.:
◉ The SAPHanaSR resource agent software package Which provide the required resources to support a standard two-node cluster were both nodes are deployed on the same network segment.
Figure 4: SAPHanaSR package install
◉ The cluster must include a valid STONITH method. A STONITH (Shoot the other node in the head) is a technique for fencing in computer cluster. Fencing is the isolation of a failed node so that it does not cause disruption to a computer cluster.
◉ Technical users and groups, such as <sid>adm are defined locally in the Linux system.
Figure 5: Technical users and groups
◉ Time synchronization is configured and active
Figure 6: Time synchronization check
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