#Time gal failure collection how to#
#Time gal failure collection manual#
#Time gal failure collection full#

The default value of this parameter is вЂ trueвЂ™ and has to be explicitly changed on the secondary instance to operate with reduced memory. During a takeover, the instance with lower priority (QAS) can be shutdown to make the underlying host resources available for production workloads.ДЇor both the scenarios, the secondary HANA database instance configuration is set to preload_column_tables = false. This setup requires additional storage to operate the additional instance(s). When replicating between AWS regions, the recommended replication mode is async for HSR due to increased latency.ДЄ common use case for a shared secondary scenario is to operate an active quality (QAS) instance along with the secondary HANA database instance on the same host, also called MCOS (Multiple Components One System). However, such a deployment is also possible across multiple AWS regions. The following diagram illustrates the deployment of a smaller secondary in a separate Amazon Web Services(AWS) Availability Zone within the same region.

#Time gal failure collection manual#

Given the manual intervention required and the time taken following a takeover to load the column tables before the HANA database is open for SQL connections, these scenarios are more relevant for a Disaster Recovery (DR) than a High Availability (HA) solution. This configuration needs to be changed to вЂ trueвЂ™ before promoting this instance as primary. The specific configuration to implement this change is to set the HANA database parameter preload_column_tables to false. In both these scenarios, preload of column tables is disabled on the secondary HANA database. SLES documentation refers to this as вЂ Cost Optimized ScenarioвЂ. Shared secondary is where the unused memory is utilised by a non-production or sacrificial instance. This is sometimes referred to as Pilot Light DR as in the blog Rapidly recover mission-critical systems in a disaster. Smaller secondary is where the infrastructure is sized smaller than the primary, and then re-sized on takeover. In this blog we differentiate between them with the terms вЂ smaller secondaryвЂ™ and вЂ shared secondaryвЂ™. There are two common architectures for deploying a secondary HANA database with a lean, or reduced memory footprint in AWS.

#Time gal failure collection how to#

This blog aims at providing a detailed guidance on how to size the secondary HANA database instance while operating with reduced memory footprint with examples for multiple deployment scenarios. If the secondary instance is not sized correctly, this can lead to out-of-memory crashes and reduced resilience. Even by disabling HANA column table loading, the memory demands on the secondary host can go beyond 60% of the actual production HANA memory usage. The actual memory demand on secondary host is highly dependent on the HANA System Replication (HSR) configuration and production data change rate.

#Time gal failure collection full#

A restart is required before promoting it to be primary, at which time it is assumed that the full memory requirement is available. The reduced memory requirement in the secondary HANA node is achieved by configuring the secondary to not load HANA column data into main memory. This can result in considerable cost savings for compute, either by choosing a smaller instance size or leveraging excess memory on the secondary to operate other SAP HANA database workloads. However, if a higher RTO is acceptable, it is possible to operate the secondary HANA database instance with a reduced memory footprint. To achieve a near zero Recovery Time Objective (RTO), it is necessary for the primary and secondary HANA database instances to have a similar memory capacity. In Amazon Web Services(AWS), the secondary HANA database instance can either exist within the same region (different Availability Zone) or in a separate region. SAP HSR continuously replicates data to ensure that in the event of a failure on the primary instance, changes persist in an alternate instance. A primary or active HANA database can be replicated to a secondary instance using SAP HANA System Replication (HSR).

SAP HANA is an in-memory database that supports mission critical workloads and is a key component of an SAP system that needs to be safeguarded from failures. SAP systems that are critical to business continuity require a well designed and tested High Availability and Disaster Recovery (HA/DR) framework to maximise application availability during planned and unplanned outages.