【正文】 loud services can be continuous. What’s more, clouds expand the types of resources available — file storage, databases, and Web services — and extend the applicability to Web and enterprise applications. At the same time, the concept of utility puting became a focus of IT design and operations. As Nick Carr observed in his book The Big Switch, puting services infrastructure was beginning to parallel the development of electricity as a utility. Wouldn’t it be great if you could purchase pute resources, on demand, only paying for what you need, when you need it? For end users, cloud puting means there are no hardware acquisition costs, no software licenses or upgrades to manage, no new employees or consultants to hire, no facilities to lease, no capital costs of any kind — and no hidden costs. Just a metered, peruse rate or a fixed subscription fee. Use only what you want, pay only for what you use. Cloud puting actually takes the utility model to the next level. It’s a new and evolved form of utility puting in which many different types of resources (hardware, software, storage, munications, and so on) can be bined and rebined on the fly into the specific capabilities or services customers require. From CPU cycles for HPC projects to storage capacity for enterprisegrade backups to plete IDEs for software development, cloud puting can deliver virtually any IT capability, in real time. Under the circumstances it is easy to see that a broad range of anizations and individuals would like to purchase “puting” as a service, and those firms already building hyperscale distributed data centers would inevitably choose to begin offering this infrastructure as a service. (4)Harnessing Cloud Computing So how does an individual or a business take advantage of the cloud puting trend? It’s not just about loading machine images consisting of your entire software stack onto a public cloud like AWS — there are several different ways to exploit this infrastructure and explore the ecosystem of new business models. Use the Cloud The number and quality of public, mercially available cloudbased service offerings is growing fast. Using the cloud is often the best option for startups, research projects, Web developers, or niche players who want a simple, lowcost way to “l(fā)oad and go.” If you’re an Inter startup today, you will be mandated by your investors to keep you IT spend to a 6 minimum. This is certainly what the cloud is for. Leverage the Cloud Typically, enterprises are using public clouds for specific functions or workloads. The cloud is an attractive alternative for: Development and testing — this is perhaps the easiest cloud use case for enterprises (not just startup developers). Why wait to order servers when you don’t even know if the project will pass the proof of concept? Functional offloading — you can use the cloud for specific workloads. For example, SmugMug does its image thumbnailing as a batch job in the cloud. Augmentation — Clouds give you a new option for handling peak load or anticipated spikes in demand for services. This is a very attractive option for enterprises, but also potentially one of the most difficult use cases. Success is dependent on the statefulness of the application and the interdependence with other datasets that may need to be replicated and loadbalanced across the two sites. Experimenting — Why download demos of new software, and then install, license, and test it? In the future, software evaluation can be performed in the cloud, before licenses or support need to be purchased. Build the Cloud Many large enterprises understand the economic benefits of cloud puting but want to ensure strict enforcement of security policies. So they’re experimenting first with “private” clouds, with a longerterm option of migrating mature enterprise applications to a cloud that’s able to deliver the right service levels. Other panies may simply want to build private clouds to take advantage of the economics of resource pools and standardize their development and deployment processes. Be the Cloud This category includes both cloud puting service providers and cloud aggregators — panies that offer multiple types of cloud services. As enterprises and service providers gain experience with the cloud architecture model and confidence in the security and accesscontrol technologies that are available, many will decide to deploy externally facing cloud services. The phenomenal growth rates of some of the public 7 cloud offerings available today will no doubt accelerate the momentum. Amazon’s EC2 was introduced only two years ago and officially graduated from beta to general availability in October 2021. Cloud service providers can: Provide new routes to market for startups and Web application developers Offer new valueadded capabilities such as analytics Derive a petitive edge through enterpriselevel SLAs Help enterprise customers develop their own clouds If you’re building large datacenters today, you should probably be thinking about whether you’re going to offer cloud services. (5)Public, Private, and Hybrid Clouds A pany may choose to use a service provider’s cloud or build its own — but is it always all or nothing? Sun sees an opportunity to blend the advantages of the two primary options: Public clouds are run by third parties, and jobs from many different customers may be mixed together on the servers, storage systems, and other infrastructure within the cloud. End users don’t know who else’s job may be me running on the same server, work, or disk as their own jobs. Private clouds are a good option for panies dealing with data protection and