Introduction to Cloud Computing

Why?

Economies of scale
- Major cloud suppliers can purchase hardware much cheaper than “regular” companies.
- If you need more computational power or storage you needn’t buy more servers, just buy more services from cloud provider.
- Ease of scaling up/down based on demand.
- No need for (traditional) IT personell. Need for DevOps increases though.

Pay as you go
- If you have more customers, you might need more processing power and storage -> pay more
- If your business is running “slower” (e.g. economic downturn) you might need fewer resources -> pay less
Low entry costs
- No long-term financial commitment
- Individual developers and start-ups can start with nearly no costs.
High availability
- Guaranteed by SLAs

Service Level Agreement

A service must provide characteristics formally negotiated in a Service Level Agreement (SLA)

Azure App Service SLA (as of September 2023)

You pay for the time a resource will be available to compute something, e.g.

You pay for a certain amount of storage space, e.g.

Sometimes it’s both storage and computational power you pay for, e.g. SQL Database

For many services you can specify the desired redundancy level:

Locally redundant storage (LRS)
- Copies your data three times within a single physical location in the primary region
- Least expensive
Zone-redundant storage (ZRS)
- Copies your data across three Azure availability zones in the primary region.
- Recommended for applications requiring high availability
Geo-redundant storage (GRS)
- Copies your data three times within a single physical location in the primary region using LRS
- It then copies your data asynchronously to a single physical location in a secondary region (again making 3 copies) that is hundreds of miles away from the primary region
- Offers durability of at least 99.99999999999999% (16 9’s)

You can scale instances at creation or during usage.

There are several options for automatically scaling resources.