The document discusses architecting for high availability on AWS. It defines high availability as having minimal downtime and being always accessible. It recommends designing for failure by avoiding single points of failure, using multiple availability zones, implementing auto-scaling for flexibility, enabling self-healing through health checks and auto-scaling, and loosely coupling components. AWS services like EC2, EBS, ELB, RDS, SQS help provide high availability when combined with these best practices. The goal is to build applications that can continue functioning even when outages occur.

1. Architecting for High Availability
Sajee Mathew
Solutions Architect

2. What is High Availability?
• Availability: Percentage of time an application operates during its work
cycle
• Loss of availability is known as an outage or downtime
– App is offline, unreachable, or partially available
– App is slow to use
– Planned and unplanned
• Goal
– No downtime
– Always available
2

3. Availability is related to
• Scalability
– Ability of an application to accommodate growth without changing design
– If app cannot scale, availability may be impacted
– Scalability doesn’t guarantee availability
• Fault Tolerance
– Built-in redundancy so apps can continue functioning when components fail
– Fault tolerance is crucial to HA
• Disaster Recovery
– The process, policies, and procedures related to restoring service after a catastrophic event
• AWS democratizes High Availability
– Multiple servers, isolated redundant data centers, regions across the globe, FT services, etc.
3

4. AWS GLOBAL
INFRASTRUCTURE

5. Regions
US-WEST (Oregon)
EU-WEST (Ireland)
AWS GovCloud (US)
ASIA PAC (Tokyo)
US-EAST (Virginia)
ASIA PAC (Sydney)
US-WEST (N. California)
SOUTH AMERICA (Sao Paulo)
ASIA PAC
(Singapore)

6. Availability Zones
US-WEST (Oregon))
EU-WEST (Ireland)
AWS GovCloud (US)
ASIA PAC (Tokyo)
US-EAST (Virginia)
ASIA PAC (Sydney)
US-WEST (N. California)
SOUTH AMERICA (Sao Paulo)
ASIA PAC
(Singapore)

7. AWS BUILDING BLOCKS
Inherently Highly Available and Highly Available with
Fault Tolerant Services the right architecture
 Amazon S3  Amazon SQS  Amazon EC2
 Amazon DynamoDB  Amazon SNS  Amazon EBS
 Amazon CloudFront  Amazon SES  Amazon RDS
 Amazon Route53  Amazon SWF  Amazon VPC
 Elastic Load Balancing  …

8. 1. DESIGN FOR FAILURE
2. MULTIPLE AVAILABILITY ZONES
3. SCALING
4. SELF-HEALING
5. LOOSE COUPLING

9. LET’S BUILD A
HIGHLY AVAILABLE
SYSTEM

14. # 1
DESIGN FOR FAILURE
●○○○○

15. « Everything fails
all the time »
Werner Vogels
CTO of Amazon

16. AVOID SINGLE POINTS OF FAILURE

17. AVOID SINGLE POINTS OF FAILURE
ASSUME EVERYTHING FAILS,
AND WORK BACKWARDS

18. YOUR GOAL
Applications should continue to function

22. AMAZON EBS
ELASTIC BLOCK STORE

27. AMAZON ELB
ELASTIC LOAD BALANCING

30. HEALTH CHECKS

36. # 2
MULTIPLE
AVAILABILITY ZONES
●●○○○

37. AMAZON RDS
MULTI-AZ

42. AMAZON ELB AND
MULTIPLE AZs

45. # 3
SCALING
●●●○○

48. AUTO SCALING
SCALE UP/DOWN EC2 CAPACITY

58. # 4
SELF-HEALING
●●●●○

59. HEALTH CHECKS
+
AUTO SCALING

64. HEALTH CHECKS
+
AUTO SCALING
=
SELF-HEALING

65. DEGRADED MODE

66. AMAZON S3
STATIC WEBSITE
+
AMAZON ROUTE 53
WEIGHTED RESOLUTION

70. #5
LOOSE
COUPLING
●●●●●

71. BUILD LOOSELY
COUPLED SYSTEMS
The looser they are coupled,
the bigger they scale,
the more fault tolerant they get…

72. AMAZON SQS
SIMPLE QUEUE SERVICE

73. PUBLISH&
RECEIVE TRANSCODE
NOTIFY

74. PUBLISH&
RECEIVE TRANSCODE
NOTIFY

81. VISIBILITY TIMEOUT

89. BUFFERING

96. CLOUDWATCH METRICS
FOR AMAZON SQS
+
AUTO SCALING

103. 1. DESIGN FOR FAILURE
2. MULTIPLE AVAILABILITY ZONES
3. SCALING
4. SELF-HEALING
5. LOOSE COUPLING

104. 1. DESIGN FOR FAILURE
2. MULTIPLE AVAILABILITY ZONES
3. SCALING
4. SELF-HEALING
5. LOOSE COUPLING

105. 1. DESIGN FOR FAILURE
2. MULTIPLE AVAILABILITY ZONES
3. SCALING
4. SELF-HEALING
5. LOOSE COUPLING

106. 1. DESIGN FOR FAILURE
2. MULTIPLE AVAILABILITY ZONES
3. SCALING
4. SELF-HEALING
5. LOOSE COUPLING

107. 1. DESIGN FOR FAILURE
2. MULTIPLE AVAILABILITY ZONES
3. SCALING
4. SELF-HEALING
5. LOOSE COUPLING

108. 1. DESIGN FOR FAILURE
2. MULTIPLE AVAILABILITY ZONES
3. SCALING
4. SELF-HEALING
5. LOOSE COUPLING

109. YOUR GOAL
Applications should continue to function

110. IT’S ALL ABOUT
CHOICE
BALANCE COST & HIGH AVAILABILITY

111. AWS ARCHITECTURE CENTER
http://aws.amazon.com/architecture
AWS TECHNICAL ARTICLES
http://aws.amazon.com/articles
AWS BLOG
http://aws.typepad.com
AWS PODCAST
http://aws.amazon.com/podcast