[php[tek] 2013] MySQL High Availability, Disaster 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.

Note: This talk was co-presented with Ligaya Turmelle

Transcript

1. MySQL HA, DR and Load Balancing 1 Friday, May 17, 13
2. •Engineer at Engine Yard on the Community Team •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, phpdoc, FRAPI and PHP internals •@dshafik Davey Shafik 2 Friday, May 17, 13
3. • PHP Women • MySQL Ace (10+ Years) • @lig • Full Disclosure Ligaya Turmelle 3 Friday, May 17, 13
4. High Availability (HA) • Not: servers that don’t die • Ensures service availability, not server availability 4 Friday, May 17, 13
5. Disaster Recovery (DR) • Process for recovering from different failure scenarios • Automated or not (or in-between) • Planning • Something to recover from • Something to recover to 5 Friday, May 17, 13
6. Load Balancing • 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) 6 Friday, May 17, 13
7. Why? • Curiosity — MySQL admin is fun • Goal: Make system predictable — then it can be automated (some) • Impacts of design decisions • Percona Cluster: oooh shiny! 7 Friday, May 17, 13
8. What • HA + Performance • Minimal code impact (drop-in system) • Simple (less moving parts) 8 Friday, May 17, 13
9. MySQL 5.5 9 Friday, May 17, 13
10. Semi-Sync Replication • Improved Data Integrity • Master blocks until 1 slave has written to relay log, flushed to disk & acknowledged • Slower... a little. • Failover to asynchronous replication 10 Friday, May 17, 13
11. 11 Friday, May 17, 13
12. Semi-Sync Master Setup •INSTALL PLUGIN rpl_semi_sync_master SONAME 'semisync_master.so'; •rpl_semi_sync_master_enabled = {0|1}; •rpl_semi_sync_master_timeout = N; 12 Friday, May 17, 13
13. Semi-Sync Slave Setup •INSTALL PLUGIN rpl_semi_sync_slave SONAME 'semisync_slave.so'; •rpl_semi_sync_slave_enabled = {0| 1}; 13 Friday, May 17, 13
14. Disaster Recovery • 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 14 Friday, May 17, 13
15. Performance • Benchmarker: 1 XL AWS Instance • Master: 1 AWS Medium Instance • Slaves: 3 AWS Large Instances (one semi- sync) • HAProxy: 1 AWS Large Instance 15 Friday, May 17, 13
16. Benchmarks • Sysbench OLTP Benchmark • 1.5 Million Rows • 64 Connection • InnoDB Storage Engine • 50,000 Queries • Optionally: Read-only 16 Friday, May 17, 13
17. Performance • Writing 1.5 Million Records, with indexes: • 1m 13s seconds (replicated) • Sysbench OLTP Benchmark: • Read/Write (with semi-sync): 2900/qps • Read/Write (without semi-sync): 2850/qps • Read only: 10850/qps 17 Friday, May 17, 13
18. MySQL 5.6 18 Friday, May 17, 13
19. Global Transaction IDs (GTIDs) • 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 19 Friday, May 17, 13
20. 20 Friday, May 17, 13
21. GTID Master & Slave Setup • gtid-mode = ON • log-bin • enforce-gtid-consistency = ON • log-slave-updates = ON 21 Friday, May 17, 13
22. GTID Slave Setup • STOP SLAVE; • CHANGE MASTER TO MASTER_HOST='<host> ', MASTER_USER='<user>', MASTER_PASSWORD='<password>', MASTER_AUTO_POSITION=1; • START SLAVE; 22 Friday, May 17, 13
23. Disaster Recovery: mysqlfailover • Performs replication health monitoring • handles automatic failover • automatic !== immediate (interval in seconds >= 5s) • Hook scripts for failed check, before/after failover, after complete recovery, 23 Friday, May 17, 13
24. Hooks • Failed check: • Alert somebody • Set app to maintenance • Before failover: • Alert somebody • Log Something • Take backups 24 Friday, May 17, 13
25. Hooks • After Failover: • Alert Somebody • After complete recovery: • Modify Application Config • Switchover elastic IPs (amazon) • Verify Application • Alert Somebody! 25 Friday, May 17, 13
26. Performance • Benchmarker: 1 XL AWS Instance • Master: 1 AWS Medium Instance • Slaves: 3 AWS Large Instances • HAProxy: 1 AWS Large Instance 26 Friday, May 17, 13
27. Performance • Writing 1.5 Million Records, with indexes: • 60 seconds (replicated) • Sysbench OLTP Benchmark: • Read/Write: 2950/qps • Read only: 9500/qps 27 Friday, May 17, 13
28. Percona XtraDB Cluster 28 Friday, May 17, 13
29. Multi-Master Replication • Everything replicates to everything • Uses XtraDB table engine (innodb compatible) — not NDB • Automatically transfer state to newly introduced nodes • Still has a “primary” server 29 Friday, May 17, 13
30. 30 Friday, May 17, 13
31. Primary Server Setup [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=<name> innodb_locks_unsafe_for_binlog=1 innodb_autoinc_lock_mode=2 31 Friday, May 17, 13
32. Other Server Setup [mysqld] wsrep_cluster_address=gcomm://<ip> 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=<name> innodb_locks_unsafe_for_binlog=1 innodb_autoinc_lock_mode=2 32 Friday, May 17, 13
33. Disaster Recovery • Choose a new Primary server • Update config • Restart all servers 33 Friday, May 17, 13
34. Performance • 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... 34 Friday, May 17, 13
35. Other Issues • 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. 35 Friday, May 17, 13
36. Read/Write Splitting $ pecl install mysqlnd_ms mysqlnd_ms.enable=1 mysqlnd_ms.config_file= /path/to/mysqlnd_ms.ini 36 Friday, May 17, 13
37. Read/Write Splitting {        "myapp":  {                "master":  {                        "master_0":  {                                "host":  "localhost",                                "socket":  "\/tmp\/mysql.sock"                        }                },                "slave":  {                        "slave_0":  {                                "host":  "192.168.2.27",                                "port":  "3306"                        }                }        } } 37 Friday, May 17, 13
38. Read/Write Splitting 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 38 Friday, May 17, 13
39. Questions? 39 Friday, May 17, 13
40. Thank You • https://joind.in/8170 • @lig | lig@phpwomen.org • @dshafik | davey@engineyard.com • http://daveyshafik.com/slides 40 Friday, May 17, 13
41. Other Resources • Semi-Sync Replication: http://bit.ly/10uT3bc • Replication with GTIDs: http://bit.ly/ THduPa • MySQL Utilities (include mysqlfailover): http://bit.ly/W98HGC • Percona XtraDB Cluster: http://bit.ly/ RtK6aP 41 Friday, May 17, 13