CloudComputing_UNIT 3.pdf
- 1. Cloud Computing Page 39 UNIT -3 Introduction to Cloud Computing • Cloud computing allowing access to large amounts of computing power in a fully virtualized manner, by aggregating resources and offering a single system view • Cloud computing has been coined as an umbrella term to describe a category of sophisticated on-demand computing services initially offered by commercial providers, such as Amazon, Google, and Microsoft. • The main principle behind this model is offering computing, storage, and software “as a service • Cloud is a parallel and distributed computing system consisting of a collection of inter- connected and virtualised computers that are dynamically provisioned • The National Institute of Standards and Technology (NIST) characterizes cloud computing as “. . . a pay-per-use model for enabling available, convenient, on-demand network access to a shared pool of configurable computing resources Common characteristics a cloud should have: • pay-per-use (no ongoing commitment, utility prices); • elastic capacity and the illusion of infinite resources; • self-service interface; and • resources that are abstracted or virtualised. • ROOTS OF CLOUD COMPUTING • Autonomic Computing: seeks to improve systems by decreasing human involvement in their operation • Autonomic, or self-managing, systems rely on monitoring probes and gauges (sensors), on an adaptation engine (autonomic manager) for computing optimizations based on monitoring data, and on effectors to carry out changes on the system. • IBM’s Autonomic Computing Initiative - four properties of autonomic systems: self- configuration, selfoptimization, self-healing, and self-protection. • Reference model for autonomic control loops of autonomic managers, called MAPE-K (Monitor Analyze Plan Execute—Knowledge)
- 2. Cloud Computing Page 40 LAYERS AND TYPES OF CLOUDS • Cloud computing services are divided into three classes: • (1) Infrastructure as a Service, • (2) Platform as a Service, and • (3) Software as a Service. • Infrastructure as a Service :A cloud infrastructure enables on-demand provisioning of servers running several choices of operating systems and a customized software stack. • Amazon Web Services mainly offers IaaS, which in the case of its EC2 service means offering VMs with a software stack that can be customized similar to how an ordinary physical server would be customized. • Platform as a Service: A cloud platform offers an environment on which developers create and deploy applications • Google AppEngine, an example of Platform as a Service, offers a scalable environment for developing and hosting Web applications Software as a Service: Traditional desktop applications such as word processing and spreadsheet can now be accessed as a service in the Web. This model of delivering applications, known as Software as a Service (SaaS)
- 3. Cloud Computing Page 41 Deployment Models • Public cloud as a “cloud made available in a pay-as-you-go manner to the general public” and • Private cloud as “internal data center of a business or other organization, not made available to the general public.” • A community cloud is “shared by several organizations and supports a specific community that has shared concerns • A hybrid cloud takes shape when a private cloud is supplemented with computing capacity from public clouds. • The approach of temporarily renting capacity to handle spikes in load is known as “cloud- bursting” • Features of a cloud • are essential to enable services that truly represent the cloud computing model • Self-Service : clouds must allow self-service access so that customers can request, customize, pay, and use services (expect on-demand, nearly instant access to resources) without intervention of human operators
- 4. Cloud Computing Page 42 • Per-Usage Metering and Billing : Services must be priced on a shortterm basis (e.g., by the hour), allowing users to release (and not pay for) resources as soon as they are not needed • Elasticity : users expect clouds to rapidly provide resources in any quantity at any time. In particular, it is expected that the additional resources can be • (a) provisioned, possibly automatically, when an application load increases and • (b) released when load decreases (scale up and down) Customization: resources rented from the cloud must be highly customizable. • In the case of infrastructure services, customization means allowing users to deploy specialized virtual appliances and to be given privileged (root) access to the virtual servers MIGRATING INTO THE CLOUD • 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. • 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. Migration can happen at one of the five levels of application, code, design, architecture, usage The migration of an enterprise application is best captured by the following where 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, and
- 5. Cloud Computing Page 43 P’OFC is the application part optimized for cloud SEVEN-STEP MODEL OF MIGRATION INTO A CLOUD Iterative Step
- 6. Cloud Computing Page 44 Migration Risks and Mitigation • The biggest challenge to any cloud migration project is how effectively the migration risks are identified and mitigated. • Migration risks for migrating into the cloud fall under two broad categories: • the general migration risks • the security-related migration risks • several issues identifying all possible production level deviants: – the business continuity and disaster recovery in the world of cloud computing service; – 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 which could help mitigate potential vendor lock-ins; On the security front - as addressed in the guideline document published by the Cloud Security Alliance. – Issues include – security at various levels of the enterprise application as applicable on the cloud in addition to issues of trust and issues of privacy. – There are several legal compliances that a migration strategy and implementation has to fulfill, – including obtaining the right execution logs as well as retaining the rights to all audit trails at a detailed level
- 7. Cloud Computing Page 45 Challenges in the Cloud • Security • Costing model • Charging model • Service level agreement • Cloud interoperability issue – Use of cloud computing means dependence on others and that could possibly limit flexibility and innovation: • The others are likely become the bigger Internet companies like Google and IBM, who may monopolise the market. • Some argue that this use of supercomputers is a return to the time of mainframe computing that the PC was a reaction against. – Security could prove to be a big issue: • It is still unclear how safe out-sourced data is and when using these services ownership of data is not always clear. – There are also issues relating to policy and access: • If your data is stored abroad whose policy do you adhere to? • What happens if the remote server goes down? • How will you then access files? • There have been cases of users being locked out of accounts and losing access to data.
- 8. Cloud Computing Page 46 UNIT -4 INFRASTRUCTURE AS A SERVICE PROVIDERS (IAAS) • Public Infrastructure as a Service providers commonly offer virtual servers containing one or more CPUs, OS, software stack, storage space and communication facilities • The most relevant features are: • (i) geographic distribution of data centers; • (ii) variety of user interfaces and APIs to access the system; • (iii) specialized components and services that aid particular applications (e.g., loadbalancers,) • (iv) choice of virtualization platform and operating systems; • (v) different billing methods and period Geographic Presence: To improve availability and responsiveness, a provider of worldwide services would typically build several data centers distributed around the world. • Availability zones are “distinct locations that are engineered to be insulated from failures in other availability zones and provide inexpensive, low-latency network connectivity to other availability zones in the same region.” • User Interfaces and Access to Servers. • Ideally, a public IaaS provider must provide multiple access means to its cloud, thus catering for various usersand their preferences. • Different types of user interfaces (UI) provide different levels of abstraction, the most common being • graphical user interfaces (GUI), • command-line tools (CLI), and • Web service (WS) APIs. Advance Reservation of Capacity.
- 9. Cloud Computing Page 47 • Advance reservations allow users to request for an IaaS provider to reserve resources for a specific time frame in the future, thus ensuring that cloud resources will be available at that time • Amazon Reserved Instances is a form of advance reservation of capacity, allowing users to pay a fixed amount of money in advance to guarantee resource availability • Automatic Scaling and Load Balancing. • As mentioned earlier in this chapter, elasticity is a key characteristic of the cloud computing model. • Applications often need to scale up and down to meet varying load conditions. • Service-Level Agreement. • Service-level agreements (SLAs) are offered by IaaS providers to express their commitment to delivery of a certain QoS. • To customers it serves as a warranty. • Amazon EC2 states that “if the annual uptime Percentage for a customer drops below 99.95% for the service year, that customer is eligible to receive a service credit equal to 10% of their bill.3” • Hypervisor and Operating System Choice: – Traditionally, IaaS offerings have been based on heavily customized open-source Xen deployments. – IaaS providers needed expertise in Linux, networking, virtualization, metering, resource management, and many other low-level aspects to successfully deploy and maintain their cloud offerings. Public Cloud and Infrastructure Services • Public cloud or external cloud • describes cloud computing - resources are dynamically provisioned via publicly accessible Web applications/Web services (SOAP or RESTful interfaces) from an off-site third-party provider, • who shares resources and bills on a fine-grained utility computing basis,
- 10. Cloud Computing Page 48 • the user pays only for the capacity of the provisioned resources at a particular time Amazon Elastic Compute Cloud (EC2) is an IaaS service that provides elastic compute capacity in the cloud Private Cloud and Infrastructure Services • A private cloud aims at providing public cloud functionality, but on private resources, while maintaining control over an organization’s data and resources to meet security and governance’s requirements in an organization. • Private clouds exhibit the following characteristics: – Allow service provisioning and compute capability for an organization’s users in a self-service manner. – Automate and provide well-managed virtualized environments. – Optimize computing resources, and servers’ utilization. – Support specific workloads. • Examples are Eucalyptus and OpenNebula “Hybrid cloud” • in which a combination of private/internal and external cloud resources exist together by enabling outsourcing of noncritical services and functions in public cloud and keeping the critical ones internal • Release resources from a public cloud and to handle sudden demand usage, which is called “cloud bursting Cloud and Virtualization Standardization Efforts • Standardization is important to ensure interoperability between • virtualization mangement vendors, • the virtual machines produced by each one of them, • and cloud computing • Distributed Management Task Force(DMTF) • initiated the VMAN (Virtualization Management Initiative), • delivers broadly supported interoperability and portability standards for managing the virtual computing lifecycle.
- 11. Cloud Computing Page 49 OVF (Open Virtualization Format • VMAN’s OVF (Open Virtualization Format) in a collaboration between industry key players: Dell, HP, IBM, Microsoft, XenSource, and Vmware. • OVF specification provides a common format to package and securely distribute virtual appliances across multiple virtualization platforms. • VMAN profiles define a consistent way of managing a heterogeneous virtualized environment • Standardization effort has been initiated by Open Grid Forum (OGF) through organizing an official new working group to deliver a standard API for cloud IaaS, the Open Cloud Computing Interface Working Group (OCCIWG) VIRTUAL MACHINES PROVISIONING • Typical life cycle of VM and its major possible states of operation, which make the management and automation of VMs in virtual and cloud environments easier Process: • Steps to Provision VM. Here, we describe the common and normal steps of provisioning a virtual server: • Firstly, you need to select a server from a pool of available servers (physical servers with enough capacity) along with the appropriate OS template you need to provision the virtual machine. • Secondly, you need to load the appropriate software (operating system you selected in the previous step, device drivers, middleware, and the needed applications for the service required). •
- 12. Cloud Computing Page 50 • Thirdly, you need to customize and configure the machine (e.g., IP address, Gateway) to configure an associated network and storage resources. • Finally, the virtual server is ready to start with its newly loaded software VIRTUAL MACHINE MIGRATION SERVICES Migration service, • in the context of virtual machines, is the process of moving a virtual machine from one host server or storage location to another • There are different techniques of VM migration, • hot/life migration, • cold/regular migration, and • live storage migration of a virtual machine VM Migration, SLA and On-Demand Computing: • virtual machines’ migration plays an important role in data centers • once it has been detected that a particular VM is consuming more than its fair share of resources at the expense of other VMs on the same host,
- 13. Cloud Computing Page 51 • it will be eligible, for this machine, to either be moved to another underutilized host or assign more resources for it • There should be an integration between virtualization’s management tools (with its migrations and performance’s monitoring capabilities), and SLA’s management tools to achieve balance in resources by migrating and monitoring the workloads, and accordingly, meeting the SLA Migration of Virtual Machines to Alternate Platforms • Advantages of having facility in data center’s technologies is • to have the ability to migrate virtual machines from one platform to another • For example, the VMware converter that handles migrations between ESX hosts; • the VMware server; and the VMware workstation. • The VMware converter can also import from other virtualization platforms, such as Microsoft virtual server machines Deployment Scenario: • ConVirt deployment consists of at least one ConVirt workstation, • whereConVirt is installed and ran, which provides the main console for managing the VM life cycle, managing images, provisioning new VMs, monitoring machine resources, and so on. • There are two essential deployment scenarios for ConVirt: • A, basic configuration in which the Xen or KVM virtualization platform is on the local machine, where ConVirt is already installed; B, • An advanced configuration in which the Xen or KVM is on one or more remote servers. Installation. The installation process involves the following: • Installing ConVirt on at least one computer. • Preparing each managed server to be managed by ConVirt. • We have two managing servers with the following Ips • (managed server 1, IP:172.16.2.22; and • managed server 2, IP:172.16.2.25) as shown in the deployment diagram
- 14. Cloud Computing Page 52 Environment, Software, and Hardware. ConVirt 1.1, Linux Ubuntu 8.10, three machines, Dell core 2 due processor, 4G RAM. • Adding Managed Servers and Provisioning VM. • Once the installation is done and you are ready to manage your virtual infrastructure, then you can start the ConVirt management console : • Select any of servers’ pools existing (QA Lab in our scenario) and on its context menu, select “Add Server.” • You will be faced with a message asking about the virtualization platform you want to manage (Xen or KVM), as shown in Figure • Choose KVM, and then enter the managed server information and credentials (IP, username, and password) as shown in Figure • Once the server is synchronized and authenticated with the management console, it will appear in the left pane/of the ConVirt, • Live Migration Effect on a Running Web Server. • Clark et al. did evaluate the above migration on an Apache 1.3 Web server; this served static content at a high rate, as illustrated in Figure 5.6. • The throughput is achieved when continuously serving a single 512-kB file to a set of one hundred concurrent clients. • This simple example demonstrates that a highly loaded server can be migrated with both controlled impact on live services and a short downtime • VMware Vmotion. • This allows users to • (a) automatically optimize and allocate an entire pool of resources for maximum hardware utilization, flexibility, and availability and • (b) perform hardware’s maintenance without scheduled downtime along with migrating virtual machines away from failing or underperforming servers • Citrix XenServerXenMotion.
- 15. Cloud Computing Page 53 • This is a nice feature of the Citrix XenServer product, inherited from the Xen live migrate utility, which provides the IT administrator with the facility to move a running VM from one XenServer to another in the same pool without interrupting the service Regular/Cold Migration. Cold migration is the migration of a powered-off virtual machine. • Main differences between live migration and cold migration are that • 1) live migration needs a shared storage for virtual machines in the server’s pool, but cold migration does not; • 2) live migration for a virtual machine between two hosts, there would be certain CPU compatibility checks to be applied; while in cold migration this checks do not apply • The cold migration process (VMware ) can be summarized as follows: • The configuration files, including the NVRAM file (BIOS settings), log files, as well as the disks of the virtual machine, are moved from the source host to the destination host’s associated storage area. • The virtual machine is registered with the new host. • After the migration is completed, the old version of the virtual machine is deleted from the source host. Live Storage Migration of Virtual Machine. This kind of migration constitutes moving the virtual disks or configuration file of a running virtual machine to a new data store without any interruption in the availability of the virtual machine’s service Aneka • Manjrasoft Aneka is a .NET-based platform and framework designed for building and deploying distributed applications on clouds. • It provides a set of APIs for transparently exploiting distributed resources and expressing the business logic of applications by using the preferred programming abstractions. • Aneka also provides support for deploying and managing clouds.
- 16. Cloud Computing Page 54 • By using its Management Studio and a set ofWeb interfaces, it is possible to set up either public or private clouds, monitor their status, update their configuration, and perform the basic management operations.