What is Cloud Computing ? and Why ?

Question

Possible Duplicates:
What is Cloud computing?
What is cloud computing?

Sorry for asking some Simple Question. But I cannot clearly understand the needs of Could Computing. or better to say I am confused about what actually Cloud Computing is. I've seen a lot of articles on this topic. But they were non technical and I cannot understand it properly.

Is Cloud Computing a replacement of dedicated Server ? If yes then why would I use it instead of dedicated Server ? What is Pay per use ? The Pricing Plans looks like VPS Hosting Plan Charts !! If I need a Service (e.g. it might be some kind of XML service) heavily used by multiple Applications. I'll put Only the Service in a dedicated server and apps might be hosted in Shared Hosting (doesn't matter). Wait a min.. Does it mean My Application hosted on a Cloud will get CDNs like Google, AOL have :( Sorry I am Confused.

I see in Google App Engine I am restricted in Python and Java Only (thats the reason I was not interested in Google App Engine much from when it released). and in an article I saw in Amazon there is no persistent storage. Hmmmm What does it mean ?? Will I've to reupload everything ?? I see I need to start VM Images there .. So do I need to pay by the time frame when my image was Up ?? But I find no reason to my Apps non-24hrs.

Sorry I am confused. Please Help me to figure it out.

Answer 1

Is Cloud Computing a replacement of dedicated Server ?

Sometimes

Depending on the service offered you upload either a virtual machine image containing all the stuff you want to run, or a single java program. It runs, you (and your customers) use it.

If yes then why would I use it instead of dedicated Server ?

You need a database server today - instead of waiting for Dell to deliver it, you to check out the HW, isntall the OS, configure it, get the netowrk working, cool it, manage it, secure it. Then you service takes off and you need 100 servers tomorrow, or you have a business model that needs 100 servers on the last day of the month but 1 server all the time. Cloud computing lets you create new servers by the minute.

What is Pay per use ?

You pay for how many cores/how many IP addresses/how many machines you use, for only thew time you use them. Unlike buying a machine and OS license for life.

Amazon there is no persistent storage.

Amazon also sells storage with their S3 product which you can use either from your cloud server or your desktop - I suspect their cloud offering uses S3 so you buy storage separately.

But I find no reason to my Apps non-24hrs.

You don't have to, most cloud users are using it to drive their website based business - stackoverflow could (but doesn't) run on the cloud. SO 24x7 availability is important - this is one of the advantages of the cloud, if a machine dies your image is instantly started on another machine possibly in another data center.

Others use it for heavy computing jobs and just buy the time on 100s of machines to complete the calculation then quit them.

Answer 2

You seem to have a lot of questions on the subject. Luckily, Wikipedia has a lot of information on the subject.

Cloud computing isn't a replacement for anything. It's a tool that can be used when appropriate.

Pay per use is an economic model that turns a product into a service to generate recurring income.

Sometimes it makes more sense, financially, to put certain parts of one's business infrastructure into "the cloud." A dedicated server is fine, if you have the resources to maintain it. You'll also need to worry about scaling, backups, failovers, etc. There's a lot that goes into it. "The cloud" puts much of that responsibility in the hands of companies who do nothing but that.

Answer 3

start by getting the definitions (here, not to repeat myself)