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assessing cloud computing Cloud Terminology

Public cloud Compute resources available for anyone to use on an on-demand, pay-for-use basis.

Private cloud Compute resources available to many constituents within a single organisation.

Hybrid cloud

A cloud comprising both private cloud and (during peak usage times) public cloud resources.

HPC cloud

A cluster with specific capabilities often required by HPC applications (e.g. compute accelerators and high-performance interconnect), delivered using a cloud business model. This type of resource often requires reservation rather than being available on demand.


Infrastructure-as-a-service: real or virtual machines; storage; and network.


Platform-as-a-Service: IaaS plus operating environment; database; web server; etc.

SaaS Software-as-a-Service: typically email; CRM; etc., but some suppliers are offering complex HPC applications using an SaaS model.

Virtualisation Most cloud offerings virtualise access to servers as it makes better use of resources, but this is not good for HPC applications as their performance could be compromised by sharing resources with other applications.

cloud platform. Te company’s HPC offering is a cluster supporting the MPI communication library for parallel applications. OpenStack is proving to be popular with academics, as they can not only use it to run highly parallel workloads, but they can also contribute to the open-source community. T Systems has a wide range of mainstream hosted and cloud services, including a shared grid service, and an HPC-cloud offering that provides dedicated resources on an on-reservation basis. T Systems participates in the European Commission- funded Helix Nebula project.

Community initiatives Cloud offerings provided for HPC users are evolving rapidly, as the previous section demonstrates. But is the user community also evolving in order to be able to exploit these offerings? Two initiatives, the Helix Nebula project and the Uber-Cloud Experiment, suggest



Te motivation for the Uber-Cloud project

( came from a series of conversations between Wolfgang Gentzsch and Burak Yenier, who wanted to better understand how real are the perceived problems that constrain running HPC in the cloud. Tese problems include concern about privacy and security, unpredictable costs, ease of use, application performance and soſtware licensing. (Te last of these is an issue that many independent soſtware vendors (ISVs) still need to address as cloud-based licenses for HPC applications are the exception rather than the rule.) Te experiment was planned to help address these concerns. Te project has no funding and is backed by no commercial or governmental organisation. It is a labour of love, and an opportunity to build a community that may change the way that high-performance computing delivers value to businesses. Te objective of the experiment is to explore the end-to-end process for scientists and engineers as they access remote HPC facilities on which to run their applications. Te first round of projects ran from August to October 2012, with the project now considering the 4th round of proposals. Te requirements of users on HPC cloud

facilities vary enormously, as do the capabilities of HPC clouds, so it is important to pick the

that good progress is being made. Helix Nebula is a pan-European project aimed at building what it calls the Science Cloud. Te project is supported by both academia and industry and is part funded by the European Commission with the objective of developing and exploiting a cloud computing infrastructure for use by European scientists (academics, government and business). Te project is supported by three of Europe’s major research centres (CERN, EMBL and ESA) and many European providers of cloud components, including Atos, CloudSigma, Logica, SAP, T Systems, Terradue and Te Server Labs. Te project uses the OpenNebula cloud management platform, a popular tool for building HPC clouds and for providing users with ‘HPC as a service’ resource provisioning models. Open Nebula is also used by Dell, IBM, Santander, SAP, Telefonica and many hosting and cloud service providers to deliver HPC Clouds.

right cloud – not all clouds are equal. Each case study has been supported not by an individual user or a single company, but by a team comprising users, soſtware providers, resource providers and experts in HPC and cloud computing. Tis approach has been invaluable in ensuring that someone in the team is always able to understand issues that arise such as scalability, soſtware licensing or application performance. Te case studies reported by the experiment (the report is available on their web site) are extremely valuable to anyone wanting to understand the big issues before taking their first steps in the cloud.

Grid is dead, long live the cloud Grid and cloud are imprecise terms. More than a decade ago people were using the term grid to describe many flavours of distributed computing, but suddenly the word seemed to disappear. Today the term cloud is fashionable. Everything is ‘in the cloud’ even if what is really meant is that something is accessible over the internet. One of the interesting aspects of the evolution of HPC in the cloud is that some of the solutions being offered look more like grids than clouds. But the terms used don’t matter, what is

important is whether HPC in the cloud actually works. Te question asked in the title of this article was ‘is it real?’ Te answer, with some caveats around topics such as virtualisation, latency and soſtware licensing, is a resounding yes. Clouds have evolved to provide better support for HPC, and the HPC community has responded by embracing cloud. Tere are still problems to be solved and lessons to be learned, but HPC is well on its way to being a first-class citizen in the cloud.

With more than 30 years of experience in the IT industry, initially writing compilers and development tools for HPC platforms, John Barr is an independent HPC industry analyst.

@scwmagazine l

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