Multi-node sites give you high availability, but come with their own constraints and challenges. Hear the team from WP Engine as they talk about how to optimize your high-availability WordPress sites on AWS instances.

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Introduction to scaling your
WordPress site past a single node
using AWS
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Adrian R. SanMiguel, Amazon Web Services
Rob Janney and Jason Stallings, WP Engine

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Ask questions as we go.
We’ll answer as many questions as we can after
the presentation
Slides and recording will be
made available shortly after
the webinar
Use the “Questions” pane
throughout the webinar

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What You’ll Learn
● Overview of AWS technologies
● Single node, multi-node; when to use each
● Availability zones - what they are and why it matters
● How WP Engine & AWS high-availability clusters are put together
● WordPress Tricks on multi-node

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Technical Architect
WP Engine
Rob Janney
● Sand Volleyball enthusiast
● D&D Player & DM
Sr. Partner Solutions Architect,
AWS
Adrian SanMiguel
● Avid vinyl collector (372 1st
editions)
● BBQ Pitmaster
● Trilingual (EN, SP, FR)
Senior Software Developer
WP Engine
Jason Stallings
● Lived underground
● An extra in a movie as a kid
● Manage the most starred
(GitHub) C project in Austin

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Overview of AWS
Technologies

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• Continually expanding
services to support virtually
any cloud workload
• 1957 significant services
and features released in
2018
• More than 165 fully
featured services for
customers to choose from
• Simple, pay-as-you-go
model
Customer Driven Services &
Features
Why choose AWS?
Breadth and Depth of Services
More services and functionality within those services

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Poll: Are you actively using a
multi-node setup today?

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Single-Node & Multi-Node
Architecture

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• Designed for speed and
ease-of-use
• Tightly coupled components
means that one things fails;
the rest of the application /
stack fails
• The single node holds
everything
• No easy way to scale
• No easy way to be resilient
Simple experiments, simple
workloads
Single Node
a.k.a., the monolith

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• Everything fails – all the time
• Decoupled components mean
individual app pieces can fail –
without impacting the rest of
the stack
• Stop syncing data between
individual nodes
• Pets vs cattle vs insects –
instances / Lambda /
containers are disposable
Think Big – and Resilient
Multi-Node
Break the monolith and increase HA/FT

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Availability Zones. What they
are and why it matters

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• Completely isolated
• Low latency
• Fault tolerant
• Architected for failure
Clusters of datacenters (at
least 3)
Availability Zones

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• Foundation for interaction
with AWS
• Significantly higher HA/FT
opportunity and scale over
a single Datacenter
• At least several kilometers
from other AZs
AZs are the heart of the AWS
Cloud
21 Regions (4 more on the way)
64 Availability Zones (12 more on the way)Why use AZs?

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WP Engine & AWS High
Availability Clusters

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- Survive a node failure
- Span more than one AZ
- Scale without downtime
Why expand beyond one
node?
From one to many

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- Auto Scaling Groups
- Config Management
- Service Discovery
- Container Scheduling
Automate node recovery
Automatic Recovery

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- Database Queries
- Filesystem Operations
Node spanning operations
- Caching
- AWS nitro based ec2 instances
- Prefer nodes in the same AZ
- Read only local storage
Talking across nodes adds network latency to operations
Strategies to minimize latency
Multi Node Tradeoffs: Latency

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- Cache incoherency
- Split brain failures
- Performance bottlenecks
become harder to find
New Failure Categories
- Automated testing
- HA aware monitoring
- Chaos experiments
Multiple types of nodes and many different failure cases
Strategies to deal with complexity
Multi Node Tradeoffs: Complexity

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WordPress tricks on
multi-node

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● Reduced requests to server
● More affordable storage
● Detached media
● Easier migrations!
How do you get uploads in Amazon S3?
1) WP Engine LargeFS
2) S3 Uploads plugin by Human Made
Use LargeFS!
Keeping WordPress uploads off the
hard drive

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● Partitioning of Data
● Data Replication
● Failover
● Used on WordPress.com
Built by Automattic
HyperDB
Using HyperDB to tweak the flow of
data

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Inquiring minds want to know.
Questions and answers.
* Slides, recording and resources will be made available within
the next several days

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User Guide: Auto Scaling Groups
Learn more.
AWS Landing Page
White Paper: A Dynamic Duo: WP Engine and AWS
S3 Uploads Plugin
HyperDB Codex
Speech from AWS re_Invent: Chaos Experiments

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Next up.
Register Now:
https://wpeng.in/wp-
ld/
Wednesday, June 5
11:00 a.m. CDT,
12:00 p.m. EDT,
9:00 a.m. PDT,
16:00 UTC/GMT

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Help us get better.
How helpful?
How to improve?
Future topics?

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Thank You.