The following glossary was excerpted from the Reference Model, published by the Enterprise Grid Alliance (EGA).
Commercial Enterprise Application
Directed Acyclic Graph (DAG)
Enterprise Grid Computing
Grid Management Entity (GME)
Service Level Agreement (SLA)
Service Level Objective (SLO)
Technical Enterprise Applications
Virtual Machine Manager (VMM)
Abstraction involves changing the interface of an object and exposing it in a more useful or appropriate form. This may be done by providing a layer of software, or whatever, which makes an object or collection of objects easier to manage by exposing a different object with a different interface. An example of this would be presenting the user with a tier of a service, for example of tier of web servers and their associated load balancer. The user would then manage the whole tier as a single object, including web tier attributes and load balancing policies, rather than managing each individual component.
A class of enterprise application which usually exhibits some of the following attributes:
- Multi-tier architecture.
- Interactive, as well as batch components.
- Mostly packaged, often with some customization.
- Centrally managed to enforced standards and policies
- Operational management to meet defined SLAs.
Examples include ERP, CRM etc. With respect to enterprise grids, they are typically -
- Hard to change due to architectural inertia and large installed bases.
- Not yet deployed in enterprise grid contexts, i.e. they typically have dedicated silo-ed resources such as servers and storage.
- Proprietary and not yet focused on standards support or interoperability.
A physical grid component that is a general purpose computer, such as a server.
See also: Grid Component
A directed graph containing no directed cycles, i.e. closed directed loops.
See also: Mathworld's definition.
Decommissioning is the act of putting a grid component into the destroyed state so that it is no longer available to the GME.
The applications or services that are run within modern enterprise data centers. These often exhibit some or all of the following attributes:
- Most run within a single datacenter, there being exceptions for availability, load balancing and co-operative processing.
- Most run within an Enterprise's intranet, exceptions include message-passing applications, for example stock trading applications.
Computing to support the operation of an enterprise.
An enterprise grid is a collection of interconnected (networked) grid components under the control of a grid management entity. An enterprise grid is typically managed by a single enterprise - i.e. a business entity is responsible for managing the assignment of resources to services in order to meet its business goals. THe resources and services may or may not be owned by the business, for example in the case of managed services or a service provider/outsourcer. What defines the boundaries of the enterprise grid is management responsibility and control. The services that run on an enterprise grid may range from the traditional commercial enterprise applications, such as ERP or CRM packaged applications, to newer, distributed applications or services. Enterprise grids are typically differentiated from more traditional data centers by management practices and technology, which:
- Make management service or application centric, rather than component centric.
- Enable the pooling and sharing of networked resources.
- Enable agility through rapid and automated service provisioning.
An enterprise grid may be confined to a single data center or it may extend across several.
A form of grid computing, specifically within an enterprise, resulting in an enterprise grid that includes commercial enterprise applications as a type of workload/service.
A super-class of object that represents the management functionality within the logical GME that is associated with a grid component.
The grid component is a super class of object that represents every managed entity, whether physical or logical, within an enterprise grid. Grid components are recursive, in that they may be aggregated to form other grid components, or decomposed into their constituent grid components.
Examples of grid components include, but are not necessarily limited to - Traditional resources such as servers, switches, disks, arrays and routers. These are considered to be elemental grid components.
- Less obvious resources such as a software distribution or perhaps data.
- Services, such as CRM, ERP etc.
- Everything in between.
Thus, for example, an ERP service may be decomposed into database, application server and web tiers. These may in turn be decomposed into instances that are bound to operating system instances and servers. Each of these is considered to be a grid component. Whether a grid component is viewed as a service or as a resource and depends on context. Each grid component has a life cycle which has to be managed and may encompass a number of phases, including:
The use of pools of resources onto which applications or services may be dynamically provisioned and re-provisioned to meet the goals of one or more enterprises, whilst improving both efficiency and agility. Grid computing environments may be typified by
- The use network distributed, shared pools of discrete resources to achieve greater performance, scaling, resilience and utilization
- Flexibility or mutability, as components are regularly repurposed or re-provisioned in line with the business goals for the services that run on them
- A focus on services, rather than on components, as grids turn networks into arbitrarily rich/complex fabrics of resources.
- Application or service architectures which are disaggregated or distributed in nature, for example Service Oriented Architectures (SOAs) and which leverage the properties of the fabric of resources.
- The consolidation of computing components into [typically] a smaller number of larger resource pools to enable easier provisioning and greater resource utilization.
- The standardization of components and/or their interfaces, configurations, processes and applications. Virtualization is an example of this.
The grid management entity (GME) manages all of the grid components within an enterprise grid, including -
- Their relationships with one another, for example mapping operating systems and applications onto servers and networks
- Their life cycle, for example discovering, configuring, starting and stopping components.
The GME may be realized -
- Through people and process
- Through technology
- A combination of the above.
The GME provides the context for understanding the key problems associated with managing enterprise grids and grid components today.
See Scale Out
A physical grid component that is a networking device, such as a switch or router.
See also: Grid Component
Provisioning is the act of putting a grid component into the active state so that it is available to a consumer of the service or resource it supplies.
Resources, in the most general sense, are things, usually physical or logical components, onto which services are provisioned. Resources are considered to be grid components within the context of the EGA reference model. Examples include server hardware, network switches, disc arrays, software media and so forth.
See also: Grid Component
Scale Out is the term usually applied to scaling an application or service through the use of multiple service component instances, which typically resolves to additional operating system instances and/or servers too (plus clustering frameworks of various forms). This is synonymous with Horizontal Scaling. A typical example of a service that scales out is a web server tier of a multi-tier service.
See also: Horizontal Scaling
Scale Up is usually applied to scaling an application or service by increasing service performance and/or capacity through making more resources available to an instance of a service or service component, typically within a single instance of an operating environment and/or server. This is synonymous with Vertical Scaling.
See also: Vertical Scaling
A service in the most general sense is something, usually one or more software components, which responds to client requests. An electronic bookstore application is a service. The database component of the bookstore provides a data base service to the bookstore. Thus high level, abstract services may be recursively decomposed into lower level constituent services. In general, a service and all off its decomposable sub services are considered to be grid components within the context of the EGA reference model. In general the term should be qualified or its meaning made obvious through context.
See also: Grid Component
The process by which the composition or pattern of a service and the relationships with its dependencies is derived.
An agreement between the provider and consumer of a service which stipulates a set of properties or attributes that the service must satisfy, possibly together with a definition of the payment and/or penalties associated with meeting or failing to meet the agreed criteria.
See also: Service Level Objective
The specific quantifiable and measurable attributes of a service that form the basis of a Service Level Agreement.
See also: Service Level Agreement
The process by which the number, performance, scaling, availability and security attributes of grid components is derived.
A physical grid component that is a storage component, such as a disk or array.
See also: Grid Component
A class of enterprise application which usually exhibits some of the following attributes -
- Often highly parallel
- Heavily batch oriented.
- Mostly heavily customized.
Examples include Rendering, Portfolio Simulation, Finite Element Modelling etc. With respect to Enterprise Grids, they are typically -
- Easier to change due to inherent customization.
- Already deployed in some Enterprise Grid contexts.
- Often driven by cooperative processing and some focus on standards support or interoperability.
See also: Enterprise Application
Utility Computing is a term often applied to IT infrastructure and technology which really captures the fact that that infrastructure may be paid for or may deliver services which may be paid for based on use or value, rather than on component cost. Enterprise Grids, by their nature will be service centric and will require telemetry that will enable reconciliation of resources with the services that consume them, i.e. cost with value, and thus enable utility computing.
See also: Enterprise Grid Computing
See Scale Up.
A layer of software or firmware/microcode that sits between one or more operating systems and a server. It presents each hosted operating environment with the impression that it has it's own dedicated server, although in reality they all share the same physical server.
Adding a layer onto some entity so that the new entity exhibits the interface properties of the original. This layer hides the true implementation of the virtualized object so that the original can be changed or replaced without fundamentally impacting the interaction of entities that have a dependency on it. An example is disk LUNs, which present the interface of a disk, yet may be implemented as a whole disk, a partition of a disk or perhaps an aggregation such as a RAID stripe.
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