Analogy
- When an electric appliance needs power, we plug it in into socket
- Electricity is readily available in our home but actuall generated over power stations
- We pay the electricity bill for whatever we have used bcoz electricity is metered
- If we apply the same analogy to software/information technology services, this is what cloud exactly does.
Pictorial Representation
Experiment: We are starting a new project for airline reservations
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Sample architecture will be as shown below
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Number of Server required to run this architecture at a bare minimum are 5
- Availability Checker
- Booking Server
- Ticket Generator
- Database
- Gateway
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Where will these servers be located physically?
- On-Premise Datacenter
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What will you do if Database crashed?
- If the database is crashed whole application will be down
- To resolve this, we will add a secondary database which has data in sync with primary database
- Now even if primary db fails we can still run the show with secodary db
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What will happen if your datacenter has caught fire ?
- This is Disaster and we need to have disaster recovery plan
- Lets go with two datacenters in two locations of our enterprise
- Pros: Effective for Disaster
- Cons: Costly and requires decent connectivity between two sites
- Lets go with only storing the backup in other site
- Pros: Easy to implement
- Cons: In Case of disaster, this approach takes lot of time to bring back application online
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What will happen if the users to your application grow rapidly only during holiday season.
