As referenced in the last post, the book “the art of scalability” provided a very good approach to cloud architectures or what has to be done. They also define some other great principles, resulting in 12 design principles for software architectures. Most of the principles are very interesting for cloud computing as well.
1. N+1 Design
There should be at least one additional System. Normally you should have 3 Systems. Premise: one System for me, one System for the Customer and one System for the Errors
2. Design for Rollback
Applications should always be able to be downgraded. It should be easy to downgrade a System in case of an Error.
3. Design to be Disabled
It must be necessary to disable a System or Parts of it, if there are problems. However, the overall System should not be effected by this.
4. Design to be Monitored
Not only IO or CPU Performance is important, it is more about „intelligent“ Monitoring. We want to know the following:
- When does the System act different as normal?
- What future loads will I have?
5. Design for Multiple Live Sites
Backup and Recovery Centers should also carry parts of the load. If you have additional datacenters, you should use them for load, not just for recovery.
6. Use Mature Technologies
No Beta or CTP Versions but use versions that are stable.
7. Asynchronous Design
Asynch operations are more error-prone. However, they are harder to test.
8. Stateless Systems
Statefull Systems affect the system performance in a negative way and make scalability harder.
9. Scale Out, Not Up!
Scaling should be intelligent. Build a smart architecture that reduces load! Adding more Servers doesn‘t always solve the problem!
10. Design for at Least Two Axes of Scale
Divide Systems in different Parts. Scale Horizontal and vertical!
11. Buy When Non Core
Only use core competences that are already in the company. If it is not a core competency, buy it!
12. Use Commodity Hardware
High-End Hardware is more expensive
Picture Copyright by Moyan Brenn
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