High Availability Deployment
High Availability Deployment
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High availability (HA) refers to a system's ability to operate continuously with minimum downtime. It's about ensuring that critical systems and applications are accessible and reliable, even in the face of unexpected events or failures.
Overview
Nexus Repository accomplishes HA by deploying a cluster of redundant instances, or nodes, running simultaneously within a single data center. This model improves uptime as at least one node of Nexus Repository is available to receive requests in the event that other instances are unavailable.
See Requirements for High Availability
Application Load Balancer
The Nexus Repository nodes are behind an application load balancer that monitors the availability of the nodes and distributes requests to available instances.
Shared External PostgreSQL Database
The instances connect to a shared external database on separate hardware and managed independently from Nexus Repository.
Shared Object Blob Storage
Components are stored in shared blob stores located on network storage or object-based storage. Each instance requires low-latency access to the shared storage.
Nexus Repository Instances
Each Nexus Repository instance should run on separate hardware to avoid losing multiple nodes due to a single point of failure. A minimum of two nodes are required for HA deployments.
Additional nodes provide extra redundancy to handle more capacity to allow for scaling of the cluster. Keep in mind that the network's bandwidth and the database's hardware are the limiting factors as you scale up the number of nodes in a cluster.
Related Topics
Install in HA deployment using the OpenShift Operator
Follow the steps outlined in the OpenShift Operator documentation.
See OpenShift Operator.
Migrating from the Legacy HA-C deployment
Follow the instructions for migrating from a Legacy HA-C Deployment KB article.
See Migrating from a Legacy HA-C Deployment
Upgrades in an HA environment
Nexus Repository 3.71.0 supports zero downtime upgrades. For details, see our help topic on upgrading Nexus Repository using rolling upgrades.
Updating to the helm chart with shared logging
As of Nexus Repository 3.68.0, the Helm chart uses a shared logging location.
Content selector difference in an HA environment
Learn the differences in how content selectors work in HA deployments.
See Content Selectors
SQL Search
While all Nexus Repository instances on versions 3.88.0 and beyond use SQL search, earlier versions used Elasticsearch for standalone instances and SQL search in HA environments. If you are migrating to HA in versions before 3.88.0, make sure to learn the differences you can expect in search behavior. See SQL Search
Default blob store
Enabling HA removes the default blob stores on new instances. Review the follow the instructions to change your default blob stores to a shared location.
See Moving Blob Storage