Important definitions


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Definition

Client

A piece of software that accesses system services through the API. The client acts as an agent for a consumer, making allocation requests on the consumer’s behalf.

Cluster

A cluster is a group of loosely coupled computers (hosts) that work together on a shared computing infrastructure. Within EGO, this group of hosts is managed by a single vemkd daemon that runs in the background on the master host.

An EGO cluster has one master host that controls the rest of the cluster. Clients that interact with the cluster interact with the master host first, then are allocated cluster resources that they can use directly. The software automatically distributes the cluster resources fairly among various competing resource consumers.

Once the cluster is constructed and running, an administrator defines consumers and users, adds resource distribution policies, deploys services, and registers applications that can run on the cluster. Then the cluster is ready to serve clients.

Consumers

A consumer represents an entity that can demand resources from the cluster. A consumer might be a business service, a business process that is a complex collection of business services, an individual user, or an entire line of business.

Host roles

Hosts in the cluster may be described as the master host, master candidates, management hosts, compute hosts, the web server host, or the DB host.

EGO_TOP and EGO_CONFDIR

This document uses EGO_TOP to describe the top-level EGO directory (where EGO is installed). %EGO_CONFDIR% (Windows) or $EGO_CONFDIR (Unix) is an environment variable and is used when the document is describing where configuration files can be found. When you have enabled failover, this directory differs from EGO_TOP.

Resources

Resources are physical and logical entities that can be requested by a client. For example, an application (client) requests a CPU (resource) to run.

Resources also have attributes. For example, a host has attributes of memory, CPU utilization, operating systems type, etc.

Services

A system service is an internal service that is responsible for running part of the infrastructure. System services may have multiple concurrent service instances running on multiple hosts. All system services (except for derbydb) are automatically enabled by default at installation.