MIGRATING INTO A CLOUD

 

MIGRATING INTO A CLOUD

INTRODUCTION:

• Cloud computing is a disruptive model of IT whose innovation is part technology and part business model.

• In short a “disruptive techno-commercial model” of IT.

• This chapter focuses on the key issues and associated dilemmas faced by decision makers, architects, and systems managers in trying to understand and leverage cloud computing for their IT needs.

• We will discuss the key factors for each of the above questions and a Seven-Step Model of Migration into the Cloud.
• Several efforts have been made in the recent past to define the term “cloud computing” and many have not been able to provide a comprehensive one.

We propose the following definition of cloud computing: “It is a techno-business disruptive model of using distributed large-scale data centers either private or public or hybrid offering customers a scalable virtualized infrastructure or an abstracted set of services qualified by service-level agreements (SLAs) and charged only by the abstracted IT resources consumed.”

THE PROMISE OF THE CLOUD:

• Most users of cloud computing services offered by some of the large-scale data centers are least bothered about the complexities of the underlying systems or their functioning.
• So given the heterogeneity of either the systems or the software running on them. They were most impressed by the simplicity, uniformity, and ease of use of the Cloud Computing Service abstractions.

• The cloud computing services, now popularly called “cloudonomics,”

Cloudonomics:

• ‘Pay per use’ – Lower Cost Barriers
• On Demand Resources –Autoscaling
• Capex vs OPEX – No capital expenses (CAPEX) and only operational

Expenses OPEX.

• SLA driven operations – Much Lower TCO
• Attractive NFR support: Availability, Reliability

Technology:

• ‘Infinite’ Elastic availability – Compute/Storage/Bandwidth
• Automatic Usage Monitoring and Metering
• Jobs /Tasks Virtualized and Transparently ‘Movable’
• Integration and interoperability ‘support’ for hybrid ops
• Transparently encapsulated & abstracted IT features

THE CLOUD SERVICE OFFERINGS AND DEPLOYMENT MODELS:

• IT managers and system administrators preferred IaaS as offered by Amazon for many of their virtualized IT needs,

• The programmers preferred PaaS offerings like Google AppEngine (Java/Python programming) or Microsoft Azure (.Net programming).

• Users of large-scale enterprise software invariably found that if they had been using the cloud, it was because their usage of the specific software package was available as a service—it was, in essence, a SaaS offering. Salesforce.com was an exemplary SaaS offering on the Internet.
• From a technology viewpoint, as of today, the IaaS type of cloud offerings have been the most successful and widespread in usage.
• However, the potential of PaaS has been high: All new cloud-oriented application development initiatives are based on the PaaS model.

• search (Google/Yahoo/Bing, etc.) or
• Email Gmail/Yahoo mail/Hotmail, etc.) or
• Social networking (Facebook/Twitter/Orkut, etc.)
• The cloud application deployment and consumption was modeled at three levels:
• The public cloud offerings from cloud vendors;
• The private cloud initiatives within large enterprises;
• The hybrid cloud initiatives that leverage both the public cloud and the private cloud or managed services data centers.

• The IaaS oriented services offered abstracted (or virtualized and scalable) hardware—like compute power or storage or bandwidth. For example, as seen from its pricing tariffs webpage for 2009, Amazon offered six levels of abstracted elastic cloud compute (EC2) server power: the “small-instance,” “large-instance,” “extra-large instance,” “high-cpu instance,” “high-cpu medium instance,” or “high-cpu extra-large instance.” Each of these are accompanied by appropriate RAM, storage, performance guarantees, and bandwidth support.
• The PaaS offerings are focused on supporting programming platforms whose runtime implicitly use’s cloud services offered by their respective vendors. As of today, these highly vendor-locked PaaS technologies have been leveraged to develop new applications by many startups.
• The SaaS on Cloud offerings are focused on supporting large software package usage leveraging cloud benefits.

CHALLENGES IN THE CLOUD:

• The promise of the cloud seems very similar to the typical distributed systems properties. Invariably either in the IaaS or PaaS or SaaS cloud services, one is proffered features that smack of full network reliability; or having “instant” or “zero” network latency; or perhaps supporting “infinite” bandwidth.

The challenges in implementing cloud computing services are plenty: Many of them are listed in below Figure.

BROAD APPROACHES TO MIGRATING INTO THE CLOUD:

• “Cloudonomics” deals with the economic grounds for leveraging the cloud and is central to the success of cloud-based enterprise usage.
• At what IT costs—both short term and long term—would one want to migrate into the cloud?
• While all capital expenses are eliminated and only operational expenses incurred by leveraging the cloud, does this satisfy all strategic parameters for enterprise IT?
• Does the total cost of ownership (TCO) become significantly less as compared to that incurred when running one’s own private data center?
• Decision-makers, IT managers, and software architects are faced with several dilemmas when planning for new Enterprise IT initiatives.

WHY MIGRATE?

• There are economic and business reasons why an enterprise application can be migrated into the cloud, and there are also a number of technological reasons.
• Many of these efforts come up as initiatives in adoption of cloud technologies in the enterprise, resulting in integration of enterprise applications running off the captive data centers with the new ones that have been developed on the cloud.
• Adoption of or integration with cloud computing services is a use case of migration.

MIGRATION OF AN APPLICATION INTO THE CLOUD:

• In brief, migration can happen at one of the five levels of

• Application,
• Code,
• Design,
• Architecture, and
• Usage.

MIGRATION OF AN APPLICATION INTO THE CLOUD:

• Either the application is clean and independent

• So it runs as is
• Perhaps some degree of code needs to be modified and adapted.
• The design (and therefore the code) needs to be first migrated into the cloud computing service environment
• Perhaps the migration results in the core architecture being migrated for a cloud computing service setting, this resulting in a new architecture being developed, along with the accompanying design and code implementation
• While the application is migrated as is, it is the usage of the application that needs to be migrated and therefore adapted and modified.

• The migration of an enterprise application is best captured by the following

• P is the application before migration running in captive data center
• P′_c is the application part after migration either into a (hybrid) cloud
• P′_l is the part of application being run in the captive local data center,
• P′_OFC is the application part optimized for cloud.
• However, when the entire application is migrated onto the cloud, then P′_l is null.
• Indeed, the migration of the enterprise application P can happen at the five levels of application, code, design, architecture, and usage. It can be that the P′_c migration happens at any of the five levels without any P′_l component.

THE SEVEN-STEP MODEL OF MIGRATION INTO A CLOUD:

SOME DETAILS OF THE ITERATIVE SEVEN-STEP MODEL OF MIGRATION INTO THE CLOUD:

BEST PRACTICES FOR MIGRATING INTO A CLOUD:

• Best Practices
  • Design for failures – underlying cloud systems are commodity items
    • Avoid Single Points of Failure in your Applications
• Develop loose coupling between applications / code / services
• Exploit key cloud features: scaling, elasticity, network locality and location independence, anonymity, support for hybrid clouds, etc.
• Build security, reliability and other non-functional requirements at every level and layer
• Rethink architectural constraints to avail cloud benefits
• Iterate and Optimize
• Beware of Vendor-Lock ins, Data Security Issues, SLAs and Pricing Honeypots
• Optimal Migration yield best ROI for using Cloud offerings
• Data and Application migration is pretty popular while more challenging is the Architecture and Design migration for PAAS and SAAS platforms – it is still evolving.

THE GENERAL MIGRATION RISKS:

• Performance monitoring and Tuning
• The business continuity and disaster recovery;
• The compliance with standards and governance issues;
• The IP and licensing issues;
• The quality of service (QoS) parameters as well as the corresponding SLAs committed to;
• The ownership, transfer, and storage of data in the application;
• The portability and interoperability issues;
• The issues that result in migration failure and loss of business confidence in these efforts.

SECURITY-RELATED MIGRATION RISKS:

• Trust and privacy.
• Obtaining the right execution logs as well as retaining the rights to all audit trails at a detailed level—which currently may not be fully available.
• However, the robustness of the solutions to prevent data loss is not fully validated.
• Key aspects of vulnerability management and incident responses quality are yet to be supported in a substantial way by the cloud service vendors.
• Finally there are issues of consistent identity management as well.