Silo-Based Architectures for High Availability Applications @CodeCampCluj

SILO-BASED ARCHITECTURES

Georgiana Gligor Tekkie Consulting

FOR HIGH AVAILABILITY APPLICATIONS

CodeCamp Cluj May 2016

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

3


Agenda

✓who needs to address high availability?

✓describe high availability

✓silos: a possible approach

✓advantages and disadvantages

4


Software industry is

built around

anticipating change.

David Scott Bernstein, “Beyond Legacy Code”

5

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

YOUR APPLICATION


Standard Application Components

7




master

FrontendBusinessLogic

FrontendFrontend

Browser

internetLoad

balancer

slave

reads writes

How Do You Adjust?

10


master


FrontendFrontend

Browser

internetLoad

balancer

slave

reads writes

How Do You Adjust?

11

redundancy


master


FrontendFrontend

Browser

internetLoad

balancer

slave

reads writes

How Do You Adjust?

12

resilience


Typical Application Layering


Application Components


HIGH AVAILABILITY


Ability to access the system:

✓ retrieve information

✓ alter information

✓ send new data

Availability

16


Downtime

▸ scheduled

▸ unscheduled

17


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


A man's got to know

his limitations.

Dirty Harry

19

http://www.imdb.com/title/tt0070355/quotes


HA System Design Principles

1. eliminate single points of failure

2. reliable crossover

3. detect failures as they occur

20


SILOS


Departments inside a company do not

work together.

Silo Mentality

22


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 %


Application Components (again)


Happens to the Best


Silo-Based Architecture


Silos: Multiple Caches


Silos: A/B Testing


Silos: Live Upgrades


Advantages

✓ real A/B testing

✓ no BHUF requirements

✓ no disruption => brand loyalty

✓ lower TCO

✓ simplify scalability

✓ avoid unneeded complexity by reusing familiar

technologies30


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

31


TAKEAWAYS



Takeaways

✓ build situational awareness with clever

monitoring

✓ automate outage detection

✓ powerful A/B testing

✓ think long-term

34


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

35

https://en.wikipedia.org/wiki/High_availability

http://docs.openstack.org/ha-guide/intro-ha-concepts.html

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=5487204

https://www.whitehouse.gov/the-press-office/2013/02/12/presidential-policy-directive-critical-infrastructure-security-and-resil

https://pragprog.com/book/dblegacy

https://www.varnish-software.com/products/varnish-plus


Q & A

THANK YOU!

Discover. Design.

Develop. Deliver.

Georgiana Gligor

@gbtekkie

https://twitter.com/gbtekkie

Technology

Silo-Based Architectures for High Availability Applications @CodeCampCluj