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Arbiter

An arbiter node is a cluster member that does not process data but provides stability to cluster technologies. The arbiter node is crucial for high availability in the cluster with two data nodes and ensures cluster stability.

Why is the Arbiter important

Multiple cluster technologies in LogMan.io use election algorithms to assign a master node. Only with odd number (2n - 1) of nodes in the cluster the election can have only one winner. All the technologies are equipped with scenarios how to work in cluster with even number of nodes. However, providing the odd number of nodes brings stability, especially during incidents when one of the cluster nodes might be disconnected.

An arbiter node is not required in a cluster setup with three core nodes.

The arbiter node can run on small hardware server or on a virtual server. It MUST not be collocated on the same hardware server as another TeskaLabs LogMan.io cluster node.

Note

You may also see the arbiter node referred to as a quorum or witness node.

Specification of the Virtual machine

  • CPU: 4 vCPU
  • RAM: 32 GB
  • SWAP: 4 GB

Storage

  • OS /: 50 GB, thick provisioning
  • Docker /var/lib/docker: 50GB, thin provisioning
  • SSD disk /data/ssd: 100 GB, thick provisioning
  • HDD disk /data/hdd: 100 GB, thin provisioning

Can be provisioned from the virtualization platform or use LVM to divide a singular storage space.

Operating System

Linux Ubuntu Server LTS 22.04 (minimal version)