Percona Cluster ( Galera ) is one of the best database solution that provides synchronous replication. The feature like automatic recovery, GTID and multi threaded replication makes it powerful along with ( XtraDB and Xtrabackup ). A good solution for MySQL HA.

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MySQL HA Solution - Percona Cluster

2. Agenda
• Need for HA
• Principle of Distributed computing.
• MySQL HA Solutions Available.
• Introduction to Galera.
• Percona Cluster.
• Node Recovery.
• Things to be considered.
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3. 3
• Senior MySQL DBA Yahoo!
• Focus MySQL HA and Sharding
• MySQL Experience 4 Years
• Student MS ( FOSS ) MIT
• Blogger remotemysqldba.blogspot.in
About Myself : P.R.KarthiK

4. Need For HA
• Site Reliability
• Failover
• Disaster Recovery
• Scheduled / Unscheduled downtime.
• Avoid Single Point Failure
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5. Principle of Distributed
Computing
CAP Theorem
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6. Principle of Distributed
Computing
CAP Theorem
•Only Two out of three
AP – MySQL Replication
CA – Galera Cluster
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7. MySQL HA Solutions Available
• Master – Slave
• Master – Master
• Single Writer
• NDB Cluster ( MySQL )
• Galera Cluster
• Tungsten Replicator
• Storage Level Replication ( DRDB)
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8. Introduction To Galera
• Founded By Codership
• Synchronous Replication
• Parallel Replication
• Multi-Threaded
• Automated node recovery
• Zero slave lag
• Read/ Write Scalable
• WAN Based Optimization.
• A True Open Source.
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9. Introduction To Galera
What is Galera ?
Galera is a replication plugin for the synchronous and
multi-master replication to achieve HA.
“Wsrep_provider_options” controls library.
Percona Cluster
MariaDB Cluster
Used over MySQL
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10. Introduction To Galera
• Shared nothing Architecture.
• Network is the heart.
What is wsrep ? (Write Set REPlication )
It is an API to connect the Galera library and control
characteristics. It helps to implement synchronous
replication and certification based multi-master-
replication.
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11. Introduction To Galera
Simple Architecture
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12. Percona Cluster
• Use Galera Library
• XtraDB
• Xtrabackup
+ +
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13. Percona Cluster
Why Percona Server ?
•Enhanced InnoDB (XtraDB )
•Performance Improvement
•Xtrabackup ( Makes SST better )
•A better MySQL
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14. Transaction in Galera.
• Transaction is handled by Galera Plugin.
• Uses traditional dual phase commit.
• It also handles locking.
• Uses the optimistic locking method.
• The commits are based on certifications (keys).
• Smaller transaction are always better.
• Increase in network latency increases query time.
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15. Transaction in Galera.
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16. Transaction in Galera.
• Synchronous ( Virtual ) Replication.
• Wsrep_causal_reads=ON ( true synchronous)
• Auto_increment is handled by cluster.
• Uses GTID for Transaction.
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17. Node Recovery
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• Node recovery is automated.
• Validates the gcache for state files.
• Chooses the State Transfer method
1) IST (Incremental State Transfer)
2)SST (State Snapshot Transfer )

18. Node Recovery
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IST :
•Recover from write sets in gcache.
•Faster recovery method.
•Have good gcache size.

19. Node Recovery
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SST :
State Snapshot Transfer the complete transfer
( Cloning ) of data to recreate a node.
*when not in Gcache
*Adding a new node
Different Methods of SST
Xtrabackup (best ) , rsync , mysqldump .

20. Node Recovery
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Validate Node after recovery
Wsrep_local_state_Comment
1)Joining
2)Donor/desynced
3)Joined
4)Synced

21. Things should be considered.
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• Support only Transactional engines.
• Row Based replication.
• Read commited Isolation.
• Innodb_autoinc_lock_mode=2.
• Avoid huge transactions.
• Wsrep_max_ws_rows (128K)
• Wsrep_max_ws_size. (1G)
• Network is the heart.
• Keep the DB design simple

22. IMAGE Courtesy
•Galera and Percona cluster documentation
•http://opentodo.net/2012/12/mysql-multi-master-
replication-with-galera/
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23. Queries ?
remotemysqldba.blogspot.in
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