ElastiCache is a web service that makes it easy to deploy, operate, and scale an in-memory key-value store in the cloud. The service improves the performance of web applications by allowing you to retrieve information from fast, managed, in-memory key-value stores, instead of relying entirely on slower disk-based databases. ElastiCache supports two popular open source engines – Memcached and Redis. In this webinar, we will introduce Amazon ElastiCache, go over the benefits it provides to you, discuss Memcached and Redis engines, demo how the service works, and walk you through how you can plug it into your applications in minutes. We will also cover common design patterns where using ElastiCache can dramatically improve performance of your applications, as well as reduce burden and cost of your disk-based databases, both relational and NoSQL. Learning Objectives: • Understand key Amazon ElastiCache features • Learn how to set up Amazon ElastiCache and how to integrate it into your database stack • Explore sample use cases, best practices, and tips on using Amazon ElastiCache to speed up your application by reducing database latencies and increasing throughput

1. © 2016, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Dan Zamansky, Senior Product Manager
May 26, 2016
AWS Webinar Series
Integrating Amazon ElastiCache into
Your Database Stack

2. Learning Objectives
• Understand key Amazon ElastiCache features
• Learn how to set up Amazon ElastiCache and how to integrate it into
your database stack
• Explore sample use cases, best practices, and tips on using Amazon
ElastiCache to speed up your application by reducing database
latencies and increasing throughput

3. Modern Applications Require Real-Time
Performance
We live in a connected world (IoT)
• Phones, Tablets, Cars, Air Conditioners, Toasters
Experiences are increasingly contextual
Apps need to provide real-time responses
Database performance is frequently the bottleneck
Load is spikey and unpredictable

4. Businesses Need To Be Ready For Success!

5. What is ElastiCache?

6. AWS Database Services
Compute Storage
AWS Global Infrastructure
Database
Application Services
Deployment & Administration
Networking
Performance Optimized In-Memory
Key-Value Store in the Cloud
Amazon RDS
Amazon DynamoDB Amazon Redshift
Amazon ElastiCache

7. Fully managed service = Automated Operations
In-Memory datastore self-hosted on
Amazon EC2
Amazon ElastiCache

8. In-Memory Key-Value Store
High-performance
Redis and Memcached
Fully managed; Zero admin
Highly Available and Reliable
Hardened by Amazon
Amazon
ElastiCache

9. Amazon
RDS
Amazon S3
Request Rate
High Low
Latency
Low High
Data Volume
Low High
Amazon
Glacier
Amazon
CloudSearch
Structure
Low
High
Amazon
DynamoDB
Amazon
ElastiCache
HDFS

10. ElastiCache - Customer Value
Extreme
Performance
Sub-millisecond
access latencies
Engineered for
Cloud Scale
Open Source
Compatible
Compatible with
Redis and
Memcached
Existing code will
work when you
update node end
points
Fully Managed
Automates tasks
such as failed node
replacement,
software patching,
upgrades and
backups
CloudWatch
enables you to
monitor cache
performance
metrics
Secure and
Hardened
Supports Amazon
VPC and IAM for
secure and fine
grained access.
Monitors your
nodes and applies
security patches
when necessary
Highly
Available and
Scalable
Multi-AZ with
automatic failover to
a read replica, no
human intervention
required.
Easily scale your
Redis (vertically)
and Memcached
(horizontally)
environments
Cost Effective
Pay as low as 17
cents per hour. Get
started with 750
free hours per
month of a micro
node for a year.
No cross availability
zone data transfer
costs.

11. Memcached
Slab allocator
In-memory key-value datastore
very popular as a caching solution
Supports strings, objects
Multi-threaded
Insanely fast!
Very established
No persistence
Patterns for sharding

12. Redis – the in-memory king
Powerful
~200 commands
In-memory data structure server
Utility data structures
strings, lists, hashes, sets, sorted sets,
bitmaps & HyperLogLogs
Simple
Atomic operations
supports transactions
has ACID properties
Ridiculously fast!
<1ms latency for most commands
Highly Available
Persistent
snapshots or append-only log
Open Source

13. Why Memcached and Redis?
Source: http://db-engines.com/en/ranking/key-value+store

14. Deploying ElastiCache for

15. ElastiCache with Redis - Development
Region
Availability Zone A Availability Zone B
Auto Scaling group
ElastiCache cluster
Nope

16. Primary
Availability Zone A Availability Zone B
Replica
Replica
writes
Use Primary Endpoint
reads
Use Read Replicas
Auto-Failover
 Chooses replica with
lowest replication lag
 DNS endpoint is same
ElastiCache for Redis Multi-AZ
ElastiCache
for Redis
ElastiCache
for Redis
ElastiCache
for Redis
Automatic Failover to a read replica in case of
primary node failure
ElastiCache
Automates
snapshots for
persistence

17. ElastiCache with Redis Multi-AZ
Region
Availability Zone A Availability Zone B
Auto Scaling group
ElastiCache cluster

18. ElastiCache with Redis Multi-AZ
Region
Availability Zone A Availability Zone B
Auto Scaling group
ElastiCache cluster

19. ElastiCache with Redis Multi-AZ
Region
Availability Zone A Availability Zone B
Auto Scaling group
ElastiCache cluster

20. ElastiCache with Redis Multi-AZ
Region
Availability Zone A Availability Zone B
Auto Scaling group
ElastiCache cluster

24. Redis – Read/Write Connections

25. Create Snapshot

26. Restore Snapshot

27. Restore Snapshot

28. Key Use Patterns

29. Use Case #1 - Caching
Elastic Load
Balancing
EC2 App
Instances
RDS MySQL
DB Instance
ElastiCache
Database Writes
App
Reads
Clients
Cache
Updates
Database Reads

30. Amazon
ElastiCache
Eliminate database hotspots
Predictable Performance
Cut Load on Backend
Increase Read Throughput
Reduce App Latency
Caching Will Make Your Database More Efficient
Reduce Database Cost

31. Common Caching Technique #1 – Lazy Caching:
Adding Caching to Your Application is Easy

32. Common Caching Technique #2 – Write-back caching:
Adding Caching to Your Application is Easy

33. Not if I
destroy it
first!
It’s
mine!
Very popular for gaming apps
Need uniqueness + ordering
Easy with Redis Sorted Sets
ZADD "leaderboard" 1201 "Gollum”
ZADD "leaderboard" 963 "Sauron"
ZADD "leaderboard" 1092 "Bilbo"
ZADD "leaderboard" 1383 "Frodo”
ZREVRANGE "leaderboard" 0 -1
1) "Frodo"
2) "Gollum"
3) "Bilbo"
4) "Sauron”
ZREVRANK "leaderboard" "Sauron"
(integer) 3
Use Case 2 - Real-time Leaderboard

34. Use Case 3 - Chat and Messaging
• PUBLISH and SUBSCRIBE Redis commands
• Game or Mobile chat, real-time comment streams
• Server intercommunication
SUBSCRIBE chat_channel:114
PUBLISH chat_channel:114 "Hello all"
>> ["message", "chat_channel:114", "Hello all"]
UNSUBSCRIBE chat_channel:114

35. • Popular for recommendation engines and message board ranking
• Redis counters – increment likes/dislikes
• Redis hashes – list of everyone’s ratings
• Process with algorithm like Slope One or Jaccardian similarity
• Ruby example - https://github.com/davidcelis/recommendable
Use Case 4 – Ratings
INCR item:38927:likes
HSET item:38927:ratings "Susan" 1
INCR item:38927:dislikes
HSET item:38927:ratings "Tommy" -1

36. Ex: Throttling requests to an API
Leverages Redis Counters
ELB
Externally
Facing
API
Reference: http://redis.io/commands/INCR
FUNCTION LIMIT_API_CALL(APIaccesskey)
limit = HGET(APIaccesskey, “limit”)
time = CURRENT_UNIX_TIME()
keyname = APIaccesskey + ":” + time
count = GET(keyname)
IF current != NULL && count > limit THEN
ERROR ”API request limit exceeded"
ELSE
MULTI
INCR(keyname)
EXPIRE(keyname,10)
EXEC
PERFORM_API_CALL()
END
Use Case 5 - Rate Limiting

37. Tune It Up!

38. Alarms
Monitoring with CloudWatch
• Easily Accessible via the
ElastiCache console
• Track health of your
nodes
• Set alarms to act when
need to address running
into limitations

39. Key ElastiCache CloudWatch Metrics
• CPUUtilization
• Memcached – up to 90% ok
• Redis – divide by cores (ex: 90% / 4 = 22.5%)
• SwapUsage low
• Evictions low
• CacheMisses / CacheHits Ratio low
• CurrConnections stable

40. Common Issues

41. Thundering Herd
Causes
• Cold cache – app startup
• Adding / removing nodes
• Cache key expiration (TTL)
• Out of cache memory
Large # of cache misses 
Spike in database load
Mitigations
• Script to populate cache
• Gradually scale nodes
• Randomize TTL values
• Monitor cache evictions

42. 1. Forks main Redis process
2. Writes backup to disk from child process
3. Continues to accept traffic on main process
4. Any key update causes a copy-on-write
5. Potentially DOUBLES memory usage by Redis
Swapping During Redis Backup (BGSAVE)

43. Reduce memory allocated to Redis
• Set reserved-memory field in parameter groups
• Decreases node memory available for app
Use larger cache node type
• More expensive
• But no data eviction
Write-heavy apps need extra memory
http://bit.ly/elasticache-bgsave
Swapping During Redis Backup – Mitigations

44. Redis reserved-memory Parameter

45. Recap
• In-memory data store can help address the most demanding application
requirements, as well as protect from impact of spikes in app access.
• ElastiCache is a reliable, secure and fully-managed, performance-optimized
in-memory data structure service.
• Use Multi-AZ with automatic failover for production workloads.
• Redis provides powerful capabilities for a variety of in-memory use cases
• For much more detail on setting up and using ElastiCache please see our
whitepaper (google “ElastiCache whitepaper”)

46. Free tier: 750 hours of Micro Cache Node per Month
Pay as little as $0.017 per hour thereafter
for a T2.micro node
You can get started for free

47. Thank you!