Deep Dive into MySQL InnoDB Cluster Read Scale-out Capabilities.pdf

Deep Dive into MySQL InnoDB Cluster
Read Scale-out Capabilities
MySQL Webinar Series
Miguel Araújo
Senior Principal Software Engineer
MySQL, Oracle
October 26, 2023

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1. Business requirements
2. High Availability & Disaster Recovery Architectures
3. What architecture fits my requirements?
4. MySQL InnoDB Cluster Read Replicas
5. Live Demo
Agenda
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4
It Disasters & Outages

Primary Causes
5 Copyright © 2023, Oracle and/or its affiliates. All rights reserved.
IT Disasters & Outages
On-site power failure is the biggest cause of significant outages

Costs are Rising
IT Disasters & Outages
Over half had experienced an outage costing more than $100,000

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Business Requirements

Concepts – RTO & RPO
• RTO: Recovery Time Objective
• How long does it take to recover from a single
failure
• RPO: Recovery Point Objective
• How much data can be lost when a failure occurs
Types of Failures
• High Availability:
• Single Server Failure, Network Partition
• Disaster Recovery:
• Full Region / Network failure
• Human Error:
• Little Bobby Tables
Business Requirements

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High Availability & Disaster Recovery
Architectures

Manual
• Setting up Replication topology was usually
done manually, taking many steps
Including user management, restoring backups,
configuring replication...
• MySQL only offered the technical pieces,
leaving it up to the user to setup an (always
customized) architecture
• Even required other software ... bringing lots
of work for DBA's and experts, who spent their
time automating and integrating their
customized architecture
Past

MySQL Solutions
One Product: MySQL
• All components developed and integrated
together
• MySQL Server
• Async Replication
• Group Replication
• MySQL Shell
• MySQL Router
• Full stack testing
Easy to use!
• One client: MySQL Shell
• Powerful interface to automate and integrate all
components
• Integrated orchestration and provisioning
• InnoDB Clone
• Configures the topologies in a standarized best
practice, preventing mistakes
• Transparent Access to Database
Architecture: MySQL Router
• Load balancing
• Application connection failover
• Stateless

'classic', 'asynchronous' Replication based
Solution, fully integrated
• MySQL Shell
• MySQL Router
• MySQL Server
MySQL InnoDB ReplicaSet
RPO != 0
RTO = minutes or more (manual failover)

High Availability solution based on Group
Replication, fully integrated
• MySQL Shell
• MySQL Router
• MySQL Server
• Group Replication providing:
• Automatic Failover / Fault Tolerance
• Automatic membership changes
• Network partition handling
• Consistency
• …
MySQL InnoDB Cluster
RPO = 0
RTO = seconds (automatic failover)

Disaster Tolerance Solution for InnoDB
Clusters deployments in alternate
locations, fully integrated
• High Availability (Failure within a Region)
• RPO = 0
• RTO = seconds (automatic failover)
• Disaster Recovery (Region Failure)
• RPO != 0
• RTO = minutes or more (manual failover)
• No write performance impact
• Easy to use: MySQL Shell
• Full integration of MySQL Router
MySQL InnoDB ClusterSet

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What architecture fits my requirements?

Single Region
MySQL InnoDB Cluster
• RPO = 0
• RTO = Seconds
MySQL InnoDB ReplicaSet
• RPO != 0
• RTO = Minutes or more (Manual failover)
High Availability
Best write performance
Manual Failover
🔴
🟢
Automatic failover
🟢

Multi Region
High Availability
MySQL InnoDB Cluster: Deployed over multiple regions
Multi-Region Multi-Primary
3 DC
Requires very stable WAN
Write performance affected by latency between DCs
• RPO = 0
• RTO = Seconds
🟢
🔴
🔴
🔴

Multi Region
Disaster Recovery
MySQL InnoDB ClusterSet
RPO = 0 & RTO = seconds within Region (HA)
Write performance (no sync to other region required)
Higher RTO: Manual failover
RPO != 0 when region fails
• RPO != 0
• RTO = Minutes or more
(Manual Failover)
🔴
🔴
🟢
🟢

Scaling issues
• High loads on the Cluster
members
• Primary or Secondaries
• Read intensive workloads
Special purpose instances
• Dedicated instances for
reporting
Safety
• Additional redundancy for
the dataset
Other Requirements

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MySQL InnoDB Cluster Read Replicas

Fully integrated solution for Read Scale-out

Read Scale-out
• Add any amount of async read replicas to a
Cluster
• Replicate/Failover from
• PRIMARY
• SECONDARIES
• LIST of candidates
Fully supported on
• InnoDB Cluster
• InnoDB ClusterSet

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• MySQL Shell
• Familiar interface and great usability
• Support for CLONE
• Add/remove Read Replicas online
• Configure Read Replicas and Router behavior
• MySQL Router
• No application changes needed if the topology
changes
• Chose where to send traffic
• MySQL Server Replication
• Automatic connection failover
• Automatic list of potential sources populated by
Group Replication

• Asynchronous replication connection failover ensures automatic failover of the replica’s source
• The list is automatic populated by Group Replication
• Group membership info is fetched to keep the list up-to-date
• The priority can be configured:
• Prefer to replicate from the PRIMARY
• Prefer replication from one of the SECONDARIES
• Have a LIST of possible candidates
MySQL InnoDB Cluster Read Replicas: Under the Hood
Follow the Source

• R/O traffic is routed to the Cluster’s SECONDARY members, by default
• But it can be configured, at any moment and dynamically:
• secondaries: Use only SECONDARY members
• read_replicas: Use only Read Replicas
• all: Use Read Replicas and SECONDARY members
Router’s Destination Pool

• Read Replicas do not belong to the group membership info of Group Replication
• To avoid connection failures to unreachable/unavailable members, Router implements a built-in
quarantine mechanism.
• Quarantine is configurable:
• Threshold: how many failed connections attempts are accepted until a server is put in quarantine
• How frequently should the quarantine servers be checked for health
• By default, both are set to 1.
Router’s Health Checking and Quarantine

• Add a Read Replica:
<Cluster>.addReplicaInstance(instance[, options])
• Configure Router’s destination pool:
<Cluster>.setRoutingOptions([router], “read_only_targets”, <value>)
• Change Read Replica source/failover candidates, or hide it:
<Cluster>.setInstanceOption([instance], “replicationSources”, <value>)
<Cluster>.setInstanceOption([instance], “tag: _hidden”, <value>)
MySQL InnoDB Cluster Read Replicas: Usability
AdminAPI

• Rejoin or update current Read Replica’s source :
<Cluster>.rejoinInstance(instance[, options])
• Remove a Read Replica:
<Cluster>.removeInstance(instance[, options])
• Monitor / Consult
<Cluster>.status() / <Cluster>.describe()
<Cluster>.routingOptions()
MySQL InnoDB Cluster Read Replicas: Usability
AdminAPI

• Requires MySQL Router & Shell version 8.1.0 or higher
• Requires MySQL Server version 8.0.23 or higher
• Target instance must not have any unmanaged replication channels configured
MySQL InnoDB Cluster Read Replicas: Requirements

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Live Demo

Environment
3 Regions
rome:
• 6 instances
• rome:30001, rome:30002, rome:30003, rome:30004, rome:30005, rome:30006
brussels:
• 6 instances
• brussels:30011, brussels:30012, brussels:30013, brussels:30014, brussels: 30015, brussels:30016
lisbon:
• 6 instances
• lisbon:30021, lisbon:30022, lisbon:30023, lisbon:30024, lisbon:30025, lisbon:30026
Demo
Commands used in demo available on
https://github.com/miguelaraujo/Read-Replicas-Demo

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Demo
InnoDB Cluster
• Add a read replica (default)
• Add a read replica and configure the sources
• Configure Router’s destination pool
• Hide a read replica
• Change failover candidates online
InnoDB ClusterSet
• Add read replicas to PRIMARY and REPLICA Clusters
• Configure global and individual Router’s destination pool
• Observe Router’s behavior on Switchover / Failover

Adding a Read Replica
• Familiar interface: .addInstance() vs .addReplicaInstance()
• Automatic provisioning available: Clone or Incremental
• By default, the read replica will always replicate from the PRIMARY member of the Cluster
• replicationSources allows selecting the source:
• PRIMARY
• SECONDARY
• LIST
// Add a new Read Replica to the Cluster
mysqlsh-js> cluster.addReplicaInstance("lisbon:30024")
(...)
<Cluster>.addReplicaInstance(instance[, options])

Configuring Router’s destination pool
• Familiar interface: .setRoutingOption()
• Can be changed per Router, Cluster, or ClusterSet
• Supports the following behaviors:
• secondaries
• read_replicas
• all
// Use all instances as possible destination
mysqlsh-js> cluster.setRoutingOption("read_only_targets", "all")
(...)
<Cluster>.setRoutingOptions([router], option, value)

Hiding a Read Replica
• Familiar interface: .setInstanceOption()
• Can be used to hide Read Replicas or Secondary members
// Hide a Read Replica from Router’s available destinations
mysqlsh-js> cluster.setInstanceOption("lisbon:30024", "tag:_hidden", true)
(...)
<Cluster>.setInstanceOption([instance], option, value)

Changing failover candidates
• Familiar interface: .setInstanceOption() and .rejoinInstance()
• Can be changed at any time
• .rejoinInstance() can be used to apply the changes immediately instead of only at failover time
// Change Read Replica failover candidates to use SECONDARIES
mysqlsh-js> cluster.setInstanceOption("lisbon:30024", "replicationSources",
"secondary")
// Apply the changes now
mysqlsh-js> cluster.rejoinInstance("lisbon:30024")
(...)
<Cluster>.setInstanceOption([instance], option, value)

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Demo
InnoDB Cluster
• Add a read replica (default)
• Add a read replica and configure the sources
• Configure Router’s destination pool
• Hide a read replica
• Change failover candidates online
InnoDB ClusterSet
• Add read replicas to PRIMARY and REPLICA Clusters
• Configure global and individual Router’s destination pool
• Observe Router’s behavior on Switchover / Failover

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Thank you!
Questions? Join our Slack channel
bit.ly/mysql-slack

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Deep Dive into MySQL InnoDB Cluster Read Scale-out Capabilities.pdf

Deep Dive into MySQL InnoDB Cluster Read Scale-out Capabilities.pdf

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Deep Dive into MySQL InnoDB Cluster Read Scale-out Capabilities.pdf