The document discusses silo-based architectures for high availability applications. It describes how applications can be divided into isolated "silos" to improve redundancy, resilience and the ability to perform live upgrades. Key advantages of silo architectures include enabling A/B testing without disruptions and simplifying scalability. Challenges include increased complexity for monitoring and debugging failures across silos. The presentation provides an overview of high availability concepts and argues that silo-based designs can help meet availability needs for mission critical systems.

2. SILO-BASED ARCHITECTURES
Georgiana Gligor
Tekkie Consulting
FOR HIGH AVAILABILITY APPLICATIONS
CodeCamp Cluj
May 2016

3. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016
Georgiana Gligor
✓ Geek. Mother. Do-er.
✓ Crafting enterprise-level apps
on LAMP stack since 2003
✓ Architecture and DevOps consultant
✓ PHP Cluj Meetup Organizer
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4. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016
Agenda
✓who needs to address high availability?
✓describe high availability
✓silos: a possible approach
✓advantages and disadvantages
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5. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016
Software industry is
built around
anticipating change.
David Scott Bernstein, “Beyond Legacy Code”
5

6. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016 6
YOUR
APPLICATION

7. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016
Standard Application Components
7

8. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016 8

9. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016 9

10. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016
master
FrontendBusiness
Logic
FrontendFrontend
Browser
internet
Load
balancer
slave
reads writes
How Do You Adjust?
10

11. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016
master
FrontendBusiness
Logic
FrontendFrontend
Browser
internet
Load
balancer
slave
reads writes
How Do You Adjust?
11
redundancy

12. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016
master
FrontendBusiness
Logic
FrontendFrontend
Browser
internet
Load
balancer
slave
reads writes
How Do You Adjust?
12
resilience

13. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016 13
Typical Application Layering

14. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016 14
Application Components

15. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016 15
HIGH AVAILABILITY

16. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016
Ability to access the system:
✓ retrieve information
✓ alter information
✓ send new data
Availability
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17. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016
Downtime
▸ scheduled
▸ unscheduled
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18. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016
The 9s Dance
18
Uptime Shortname
Downtime
(per year)
90.000 % one nine 36.5 days
99.000 % two nines 3.65 days
99.900 % three nines 8.76 hrs
99.990 % four nines 52.56 mins
99.999 % five nines 5.26 mins

19. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016
A man's got to know
his limitations.
Dirty Harry
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20. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016
HA System Design Principles
1. eliminate single points of failure
2. reliable crossover
3. detect failures as they occur
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21. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016 21
SILOS

22. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016
Departments inside
a company do not
work together.
Silo Mentality
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23. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016
User Behaviour
23
booking
.com
expedia
.com
imobiliare
.ro
Alexa Rank 111 429 22879
daily time
on site
10:00
mins
7:20
mins
10:30
mins
daily pageviews
per visitor
7.51 5.12 9.60
bounce rate 21.20 % 22.10 % 22.80 %

24. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016 24
Application Components (again)

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Happens to the Best

26. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016 26
Silo-Based Architecture

27. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016 27
Silos: Multiple Caches

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Silos: A/B Testing

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Silos: Live Upgrades

30. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016
Advantages
✓ real A/B testing
✓ no BHUF requirements
✓ no disruption => brand loyalty
✓ lower TCO
✓ simplify scalability
✓ avoid unneeded complexity by reusing familiar
technologies
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31. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016
Disadvantages
✓ needs razor-sharp DevOps team
✓ small increase in hardware costs on kick-off
✓ adds complexity to the monitoring layer
✓ reconsider traceability
✓ reproducing and hunting bugs is going to
change forever
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TAKEAWAYS

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34. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016
Takeaways
✓ build situational awareness with clever
monitoring
✓ automate outage detection
✓ powerful A/B testing
✓ think long-term
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35. Silo-Based Architectures For High Availability Applications - Georgiana Gligor - CodeCamp Cluj - May 2016
Further Reading
✓ Wikipedia HA page
✓ OpenStack’s HA concepts
✓ Merge Hemo report from FDA
✓ USA Presidential Policy Directive 21
✓ “Beyond Legacy Code” book
✓ Varnish Plus
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Q & A

37. THANK YOU!
Discover. Design.
Develop. Deliver.
Georgiana Gligor
@gbtekkie