[SunshinePHP 2014] MySQL HA, Recovery and Load Balancing

Using Oracle MySQL Server and Percona XtraDB Cluster we will take a look at several possible replication configurations for MySQL high-availability, disaster recovery and load-balancing. After comparing them for administration ease, scalability of reads and writes, robustness of the system for errors and time for data recovery as well as looking at how they impact your code-layer we will discuss the ins-and-outs of each setup, looking at the pros and cons, and what trade-offs you will need to make depending on your needs.

Transcript

1. MySQL HA, DR and
   Load Balancing
   

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2. Proprietary and Confidential
   •Community Engineer at
   Engine Yard
   •Author of Zend PHP 5
   Certification Study Guide,
   Sitepoints PHP Anthology:
   101 Essential Tips, Tricks &
   Hacks & PHP Master: Write
   Cutting Edge Code
   •A contributor to Zend
   Framework 1 & 2, phpdoc,
   and PHP internals
   •@dshafik
   Davey Shafik
   

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3. About These Slides
   

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4. Proprietary and Confidential
   • Two slides per “slide”!
   – Title Slide (for when I’m talking)!
   – Details slide (for later)!
   • Nobody likes it when you can read the slide just as well as the speaker
   can!
   • I like slides that are useful
   About These Slides
   

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5. High Availability
   

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6. Proprietary and Confidential
   • Not: servers that don’t die!
   • Ensures service availability, not server availability
   High Availability (HA)
   

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7. Disaster Recovery
   

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8. Proprietary and Confidential
   • Process for recovering from different failure scenarios!
   –Automated or not (or in-between)!
   • Planning!
   –Something to recover from!
   –Something to recover to
   Disaster Recovery (DR)
   

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9. Load Balancing
   

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10. Proprietary and Confidential
    • Balancing the load between multiple machines!
    –Smart (based on system resources)!
    –Dumb (round-robin)!
    • ELB is easy, but slow!
    • HAProxy is super faster (and still pretty easy)
    Load Balancing
    

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11. Why?
    

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12. Proprietary and Confidential
    • Curiosity — MySQL admin is fun!
    • Goal: Make system predictable — then it can be automated (some)!
    • Impacts of design decisions!
    • Percona Cluster: oooh shiny!
    Why?
    

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13. What
    

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14. Proprietary and Confidential
    • HA + Performance!
    • Minimal code impact (drop-in system)!
    • Simple (less moving parts)
    What
    

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15. MySQL 5.5
    

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16. Proprietary and Confidential
    • Improved Data Integrity!
    • Master blocks until 1 slave has written to relay log, flushed to disk &
    acknowledged!
    • Slower... a little.!
    • Failover to asynchronous replication
    Semi-Sync Replication
    

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17. Proprietary and Confidential
    

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18. Proprietary and Confidential
    •INSTALL PLUGIN rpl_semi_sync_master SONAME
    'semisync_master.so';
    •rpl_semi_sync_master_enabled = {0|1};
    •rpl_semi_sync_master_timeout = N;
    Semi-Sync Master Setup
    

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19. Proprietary and Confidential
    •INSTALL PLUGIN rpl_semi_sync_slave SONAME
    'semisync_slave.so';
    •rpl_semi_sync_slave_enabled = {0|1};
    Semi-Sync Slave Setup
    

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20. Disaster Recovery
    

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21. Proprietary and Confidential
    • Primary slave is pre-determined failover master!
    –Will have the most up-to-date content (not necessarily ALL the content)!
    • Slaves must re-connect to new master!
    –CHANGE MASTER to correct (new) position!
    • Switch app to new master
    Disaster Recovery
    

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22. Performance
    

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23. Proprietary and Confidential
    • Benchmarker: 1 XL AWS Instance!
    • Master: 1 AWS Medium Instance!
    • Slaves: 3 AWS Large Instances (one semi-sync)!
    • HAProxy: 1 AWS Large Instance
    Performance
    

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24. Proprietary and Confidential
    • Sysbench OLTP Benchmark!
    –1.5 Million Rows!
    –64 Connection!
    –InnoDB Storage Engine!
    –50,000 Queries!
    –Optionally: Read-only
    Benchmarks
    

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25. Proprietary and Confidential
    • Writing 1.5 Million Records, with indexes:!
    –1m 13s seconds (replicated)!
    • Sysbench OLTP Benchmark:!
    –Read/Write (with semi-sync): 2850/qps!
    –Read/Write (without semi-sync): 2900/qps!
    –Read only: 10850/qps
    Performance
    

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26. MySQL 5.6
    

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27. Proprietary and Confidential
    • Unique identifier across all server (binlogs)!
    –combines server UUID:Transaction ID!
    • Transaction based!
    • No need for log files or positions with CHANGE MASTER!
    • Consistent group-wide!
    • Easier failover
    Global Transaction IDs (GTIDs)
    

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28. Proprietary and Confidential
    

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29. Proprietary and Confidential
    •gtid-mode = ON!
    •log-bin!
    •enforce-gtid-consistency = ON!
    •log-slave-updates = ON
    GTID Master & Slave Setup
    

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30. Proprietary and Confidential
    • STOP SLAVE; !
    • CHANGE MASTER TO MASTER_HOST=' ',
    MASTER_USER='', MASTER_PASSWORD='',
    MASTER_AUTO_POSITION=1;!
    • START SLAVE;
    GTID Slave Setup
    

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31. Disaster Recovery
    

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32. Proprietary and Confidential
    • Performs replication health monitoring!
    –handles automatic failover!
    –automatic !== immediate (interval in seconds >= 5s)!
    • Hook scripts for failed check, before/after failover, after complete recovery,
    Disaster Recovery: mysqlfailover
    

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33. Proprietary and Confidential
    • Failed check:!
    –Alert somebody!
    –Set app to maintenance!
    • Before failover:!
    –Alert somebody!
    –Log Something!
    –Take backups
    Hooks
    

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34. Proprietary and Confidential
    • After Failover:!
    –Alert Somebody!
    • After complete recovery: !
    –Modify Application Config!
    –Switchover elastic IPs (amazon)!
    –Verify Application!
    –Alert Somebody!
    Hooks
    

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35. Performance
    

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36. Proprietary and Confidential
    • Benchmarker: 1 XL AWS Instance!
    • Master: 1 AWS Medium Instance!
    • Slaves: 3 AWS Large Instances !
    • HAProxy: 1 AWS Large Instance
    Performance
    

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37. Proprietary and Confidential
    • Writing 1.5 Million Records, with indexes:!
    –60 seconds (replicated)!
    • Sysbench OLTP Benchmark:!
    –Read/Write: 2950/qps!
    –Read only: 9500/qps
    Performance
    

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38. Percona XtraDB Cluster
    

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39. Proprietary and Confidential
    • Everything replicates to everything!
    • Uses XtraDB table engine (innodb compatible) — not NDB!
    • Automatically transfer state to newly introduced nodes!
    • Still has a “primary” server!
    • Based on Galera for multi-master writes
    Multi-Master Replication
    

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40. Proprietary and Confidential
    

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41. Proprietary and Confidential
    •[mysqld]

    wsrep_cluster_address=gcomm://

    datadir=/var/lib/mysql

    user=mysql

    binlog_format=ROW

    wsrep_provider=/usr/lib/libgalera_smm.so

    wsrep_slave_threads=2

    wsrep_cluster_name=benchmarking

    wsrep_sst_method=xtrabackup

    wsrep_node_name=

    innodb_locks_unsafe_for_binlog=1

    innodb_autoinc_lock_mode=2
    Primary Server Setup
    

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42. Proprietary and Confidential
    •[mysqld]

    wsrep_cluster_address=gcomm://

    datadir=/var/lib/mysql

    user=mysql

    binlog_format=ROW

    wsrep_provider=/usr/lib/libgalera_smm.so

    wsrep_slave_threads=2

    wsrep_cluster_name=benchmarking

    wsrep_sst_method=xtrabackup

    wsrep_node_name=

    innodb_locks_unsafe_for_binlog=1

    innodb_autoinc_lock_mode=2
    Other Server Setup
    

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43. Disaster Recovery
    

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44. Proprietary and Confidential
    • Choose a new Primary server!
    • Update config!
    • Restart all servers
    Disaster Recovery
    

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45. Performance
    

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46. Proprietary and Confidential
    • Unable to test!!
    • More than 4 concurrent “users” resulted in auto increment primary key
    collisions!
    • Unable to complete the benchmark at all with >= 16 threads!
    • ALERT: failed to execute mysql_stmt_execute(): Err1062 Duplicate entry

    '500519' for key 'PRIMARY'

    FATAL: database error, exiting...
    Performance
    

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47. Other Issues
    

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48. Proprietary and Confidential
    • Replication was very brittle, restarting the daemon would sometimes
    break it!
    • Restarting the server almost always break it!
    • Adding new nodes very often failed!
    • Completely unable to get the system up and running with the latest
    version for this talk.
    Other Issues
    

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49. Agenda
    mysqlnd_ms
    Read/Write Splitting
    

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50. Proprietary and Confidential
    $ pecl install mysqlnd_ms

    

    

    mysqlnd_ms.enable=1

    mysqlnd_ms.config_file=

    /path/to/mysqlnd_ms.json
    Read/Write Splitting
    

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51. Proprietary and Confidential
    {
    "myapp": {
    "master": {
    "master_0": {
    "host": "localhost",
    "socket": "\/tmp\/mysql.sock"
    }
    },
    "slave": {
    "slave_0": {
    "host": "192.168.2.27",
    "port": "3306"
    }
    }
    }
    Read/Write Splitting
    

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52. Proprietary and Confidential
    •SELECT * FROM foo; -- Use Slave!
    •/* MYSQLND_MS_SLAVE_SWITCH */SELECT * FROM foo; -- Use Slave!
    •SELECT * FROM foo; INSERT INTO bar VALUES ('baz'); -- Use Slave!!
    •/* MYSQLND_MS_MASTER_SWITCH */SELECT * FROM foo; -- Use
    Master!
    •/* MYSQLND_MS_LAST_USED_SWITCH */SELECT * FROM foo; -- Use
    whatever !
    • -- was last used
    Read/Write Splitting
    

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53. Proprietary and Confidential
    • Semi-Sync Replication: !
    –http://ey.io/18PllQP!
    • Replication with GTIDs: !
    –http://ey.io/15nTo20!
    • MySQL Utilities (include mysqlfailover): !
    –http://ey.io/GGP2Kh!
    • Percona XtraDB Cluster: !
    –http://ey.io/1gqyyUn
    Other Resources
    http://ey.io/ssp14-mysql
    

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54. Proprietary and Confidential
    Feedback & Questions:
    Feedback: https://joind.in/9093

    Twitter: @dshafik
    Email: davey@engineyard.com
    Slides: http://daveyshafik.com/slides
    http://ey.io/ssp14-mysql
    

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