Grid computing
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Cloud computing
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What?
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Grids enable access to shared
computing power and storage capacity from your desktop
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Clouds enable access to leased
computing power and storage capacity from your desktop
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Who provides the service?
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Research institutes and
universities federate their services around the world through projects such
as EGI-InSPIRE and the European Grid Infrastructure.
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Large individual companies e.g.
Amazon and Microsoft and at a smaller scale, institutes and organisations
deploying open source software such as Open Slate, Eucalyptus and Open
Nebula.
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Who uses the service?
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Research collaborations, called
"Virtual Organisations", which bring togetherresearchers around the
world working in the same field.
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Small to medium commercial businesses
or researchers with generic IT needs
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Who pays for the service?
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Governments - providers and users
are usually publicly funded research organisations, for example through
National Grid Initiatives.
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The cloud provider pays for the
computing resources; the user pays to use them
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Where are the computing resources?
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In computing centres distributed
across different sites, countries and continents.
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The cloud providers private data
centres which are often centralised in a few locations with excellent network
connections and cheap electrical power.
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Why use them?
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You don`t need to buy or maintain your own large computer centre
- You can complete more work more quickly and tackle more difficult problems. - You can share data with your distributed team in a secure way. |
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You don`t need to buy or maintain your own personal computer centre
- You can quickly access extra resources during peak work periods |
What are they useful for?
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Grids were designed to handle
large sets of limited duration jobs that produce or use large quantities of
data (e.g. the LHC and life sciences)
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Clouds best support long term
services and longer running jobs (E.g. facebook.com)
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How do they work?
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Grids are an open source technology.
Resource users and providers alike can understand and contribute to the
management of their grid
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Clouds are a proprietary technology.
Only the resource provider knows exactly how their cloud manages data, job
queues, security requirements and so on.
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Benefits?
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- Collaboration: grid
offers a federated platform for distributed and collective work.
- Ownership : resource providers maintain ownership of the resources they contribute to the grid - Transparency: the technologies used are open source, encouraging trust and transparency. - Resilience: grids are located at multiple sites, reducing the risk in case of a failure at one site that removes significant resources from the infrastructure. |
- Flexibility: users can
quickly outsource peaks of activity without long term commitment
- Reliability: provider has financial incentive to guarantee service availability (Amazon, for example, can provide user rebates if availability drops below 99.9%) - Ease of use: relatively quick and easy for non-expert users to get started but setting up sophisticated virtual machines to support complex applications is more difficult. |
Drawbacks?
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- Reliability: grids rely
on distributed services maintained by distributed staff, often resulting in
inconsistency in reliability across individual sites, although the service
itself is always available.
- Complexity: grids are complicated to build and use, and currently users require some level of expertise. - Commercial: grids are generally only available for not-for-profit work, and for proof of concept in the commercial sphere |
- Generality: clouds do not
offer many of the specific high-level services currently provided by grid
technology.
- Security: users with sensitive data may be reluctant to entrust it to external providers or to providers outside their borders. - Opacity: the technologies used to guarantee reliability and safety of cloud operations are not made public. - Rigidity: the cloud is generally located at a single site, which increases risk of complete cloud failure. - Provider lock-in: there’s a risk of being locked in to services provided by a very small group of suppliers. |
When?
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The concept of grids was proposed
in 1995. The Open science grid (OSG) started in 1995 The EDG (European Data
Grid) project began in 2001.
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In the late 1990`s Oracle and EMC
offered early private cloud solutions . However the term cloud computing
didn't gain prominence until 2007.
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