HA cluster configuration overview

To support Automation Anywhere your data center, configure an HA cluster. Follow your company methods and procedures for implementing your data center cluster.

HA clusters protect services and data in the event of a server or service failure. The following is a list of processes associated with clusters.

Database replication: Configure synchronous replication between the primary site (active) and secondary site (passive) MS SQL servers to ensure consistency in the event of a database node failure.
Downtime: The amount of downtime depends on the number of restart attempts the administrator configures for the primary server services, the number of failovers allowed per number of hours, and the failback configuration.
Failback: After the primary server is returned to normal, fail back the workload from the secondary servers to the primary servers. The primary server becomes the active server again.; Restoring operations to the primary system or site after a failover or disaster recovery on a secondary system or site.
Failover: If one of the primary servers fails, the workload of the failed server automatically shifts to the secondary server in the cluster. This automatic process is called failover. Failover ensures continuous availability of applications and data. When failover completes, the secondary server becomes the active server.; When a (primary) system detects a fault or failure, it automatically transfers control to a (secondary) duplicate system. This applies to HA clusters, where failover is from one server to another.
Graceful degradation: Process allowing cluster dependencies to operate gracefully on a degraded primary site.
Redundancy: HA clusters use redundancy to prevent single points of failure (SPOF), such as a failed server or service. HA clusters include primary (active) servers that host services or databases and secondary (passive) servers that host replicated copies of the services and databases.
Replication: The secondary servers have the same configuration and software as the primary servers, they are a duplicate (redundant copy) of the primary. Data is replicated (copied) from the primary servers to the secondary servers.

To support HA and DR for Automation Anywhere, configure the selected components in your data center for HA.

Note: In the context of clusters, though the terms server, host, and node each have specific meaning, they are frequently used interchangeably.

Cluster: A cluster is a set servers (nodes) that are connected by physical cables and software. In an HA environment, these clusters of servers are allowed to be in the same physical data center.
Cluster group (role): Group of clustered services that failover together and are dependent on each other.
Host: The cluster machine that is hosting the services.
Multiple servers: The HA technique where operations are available across multiple servers with workload managed by a load balancer. This applies to IQ Bot instances.
Node: A generic term for a machine in a cluster.
Primary node: The active node in the cluster. The machine where the production activities run. This applies to the database servers.
Secondary node: The machine that is designated as the target in the event of a failover. The secondary node is a passive duplicate of the primary node. This applies to the database servers.
Server: The machine in the cluster installed with the server operating system.

HA cluster technologies guard against three specific types of failures:

Application and service failures: These affect application software and essential services.
Site failures in multisite organizations: This is caused by natural disasters, power outages, or connectivity outages.
System and hardware failures: This affects hardware components such as CPUs, drives, memory, network adapters, and power supplies.

This ability to handle failure allows clusters to meet two requirements that are typical in most data center environments:

High availability: The ability to provide end users with access to a service for a high percentage of time and reduces unscheduled outages.
High reliability: The ability to reduce the frequency of system failure.

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