MySQL replication best practices 105-232-931
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This document provides information about Baruch Osoveskiy and the services offered by dbaces.com. Baruch is a senior consultant and DBA with over 15 years of experience working with Linux, Oracle, MySQL, and unstructured data. Dbaces provides remote DBA services, consulting, training, and support for Oracle, Microsoft SQL Server, MySQL, and PostgreSQL. They host weekly webinars on database topics and offer replication monitoring and configuration services for MySQL databases.
![mysql> show slave status
…
Last_Error : 1538
Last_Error : relay log read error……
…..
# mysqlbinlog --verify-binlog-checksum mysql_18676-relay-bin.000002
[...]
ERROR: Error in Log_event::read_log_event(): 'Event crc check failed!
Most likely there is event corruption.', data_len: 103, event_type: 2
ERROR: Could not read entry at offset 283: Error in log format or read
error.
[...]](https://image.slidesharecdn.com/5d7c2059-e53a-4caf-977d-697fc0fb6e9a-151201123857-lva1-app6892/85/MySQL-replication-best-practices-105-232-931-36-320.jpg)
![blue.my.cnf
[mysqld]
...
server-id=1
report-host=blue
binlog-format=MIXED
log-bin
log-slave-updates=true
gtid-mode=on
enforce-gtid-consistency=true
master-info-repository=TABLE
relay-log-info-repository=TABLE
sync-master-info=1
binlog-checksum=CRC32
master-verify-checksum=1](https://image.slidesharecdn.com/5d7c2059-e53a-4caf-977d-697fc0fb6e9a-151201123857-lva1-app6892/85/MySQL-replication-best-practices-105-232-931-49-320.jpg)
![white.my.cnf
[mysqld]
...
server-id=2
report-host=white
binlog-format=MIXED
log-slave-updates=true
log-bin
gtid-mode=on
enforce-gtid-consistency=true
master-info-repository=TABLE
relay-log-info-repository=TABLE
sync-master-info=1
slave-parallel-workers=2
binlog-checksum=CRC32
master-verify-checksum=1
slave-sql-verify-checksum=1
binlog-rows-query-log_events=1](https://image.slidesharecdn.com/5d7c2059-e53a-4caf-977d-697fc0fb6e9a-151201123857-lva1-app6892/85/MySQL-replication-best-practices-105-232-931-50-320.jpg)
![On Master:
[mysqld]
rpl_semi_sync_master_enabled=1
rpl_semi_sync_master_timeout=1000 # 1 second
On each Slave:
[mysqld]
rpl_semi_sync_slave_enabled=1](https://image.slidesharecdn.com/5d7c2059-e53a-4caf-977d-697fc0fb6e9a-151201123857-lva1-app6892/85/MySQL-replication-best-practices-105-232-931-51-320.jpg)
MySQL replication best practices 105-232-931
- 2. Baruch osoveskiy Senior Consultant in dbaces.com Linux-Unix SYSADMIN form 1997 DBA on Oracle and MySQL Since 2000 Working with unstructured Data (“big data”) since 2000 like text and spatial
- 3. Oracle and Microsoft Partners Oracle Aces and Ace Directors What we do ◦ Remote DBA services ◦ Database consulting and projects ◦ Oracle identity and access management ◦ Training Platforms ◦ Oracle DB ◦ Microsoft SQL Server ◦ MySQL ◦ PostgreSQL
- 5. One webinar each week Webinar recording will be available on site a few days after webinar Check our webinars schedule @ http://www.dbaces.com/training/upcoming-webinars subscribe to get updates @ www.dbaces.com
- 6. MySQL replication Introduction New features in MySQL 5.6 replication How to Create MySQL replication with hot- backups How To monitor MySQL replication
- 9. • High availability – can promote slave to master • Scale Out – add multiple read slaves • Analytics – can run Analytics on live data. • Backup – run cold backup on slave. • For DEV and Pre-Prod
- 10. Replication Formats • SBR - Statement Based Replication • Nondeterministic function problem • RBR - Row Based Replication • High network usage • Higher IO usage • Mixed Mode
- 11. Not safe Nondeterministic function FOUND_ROWS(), GET_LOCK(), IS_FREE_LOCK(), IS_USED_LOCK(), LOAD_FILE(), MASTER_POS_WAIT(), RELEASE_LOCK(), ROW_COUNT(), SESSION_USER(), SLEEP(), SYSDATE(), SYSTEM_USER(), USER(), UUID(), and UUID_SHORT().
- 12. Where the Changes Stored • Binary Log – Master (blue-bin.000002) • Relay Log – Slave (white-relay-bin.000003)
- 13. Replication Threads • Master Server • Binlog Dump Thread • Slave Server • IO Thread • SQL Thread
- 14. Method of Sending the Data (Replication Type) • Asynchronous Replication • Semi-Synchronous Replication (5.5 )
- 17. Master TRX1 TRX2 TRX3 . Slave TRX1 TRX2 TRX3 . 1 2 3 Binary log Relay Log IO Thread DML + COMMIT
- 20. Pros • Fast • slave can be disconnected Cons • Potential loss of transactions and data integrity
- 23. Master TRX1 TRX2 TRX3 . Slave 1 Binary log DML IO Thread 2 3 4 IO Thread TRX1 TRX2 TRX3 . Relay Log
- 24. Master TRX1 TRX2 TRX3 . Slave TRX1 TRX2 TRX3 . 1 2 3 4 Binary log Relay Log IO Thread IO Thread DML
- 27. Pros • data integrity • Commit ensure the transaction will copy to slave Cons • Performance Implications • The transaction need to Wait for the slave to commit • Problematic in high DML load
- 28. What's New • Multi threaded Slave • Relay log recovery • Binary Log Group Commit • Crash-safe Replication – Binlog Checksums • Global Transaction ID You can read more in: http://dev.mysql.com/tech-resources/articles/whats-new-in-mysql-5.6.html
- 29. Replication performance is improved by using multiple execution threads to apply replication events slave-parallel-workers=2 You can read more in: http://dev.mysql.com/tech-resources/articles/whats-new-in-mysql-5.6.html
- 30. • slave can automatically recover from a failure and resume replicating DML updates • the slave can roll back replication to the last successfully committed transaction relay-log-recovery =1 You can read more in: http://dev.mysql.com/tech-resources/articles/whats-new-in-mysql-5.6.html And in Bug #13893363
- 31. • Commit a group of transactions to the binary log. • Ensures durability with good performance. • Designed to handle seamlessly temporary peeks on the workload. enable by default in 5.6 You can read more in: http://dev.mysql.com/tech-resources/articles/whats-new-in-mysql-5.6.html
- 33. Master and slave can have different data • Non deterministic queries. • Wrong use of replication filters. • Write executed on slave outside the. replication (slave is not read only) • Binlogs or relay log corruption.
- 34. How to check ? Before 5.6 you can use only : • show slave status • pt-table-checksum • utilty from precona that can check table checksum
- 35. • First enable checksum on the master binlog_checksum = CRC32; master_verify_checksum = on; • Then start binlog verify on the slave slave_sql_verify_checksum = on; * From >= 5.6.6 enable by default
- 36. mysql> show slave status … Last_Error : 1538 Last_Error : relay log read error…… ….. # mysqlbinlog --verify-binlog-checksum mysql_18676-relay-bin.000002 [...] ERROR: Error in Log_event::read_log_event(): 'Event crc check failed! Most likely there is event corruption.', data_len: 103, event_type: 2 ERROR: Could not read entry at offset 283: Error in log format or read error. [...]
- 37. Pros • Can help to find error in the bin log/relay log • Notify on a bin log corruption Cons • More CPU for the CRC • The MySQL will keep writing to the corrupt bin log
- 39. • Transactions are not guaranteed to execute in the order of the Binary logs • The show slave status is not accurate
- 41. • The same event can have different Binary log file and position on different slaves • Hard to find inconsistency in replication • Very problematic to reconfigure replication
- 42. • Unique identifier of a transaction across all servers in replication topology The GTID look like : GTID = source_id:transaction_id Where transaction_id = transaction_start-transaction_stop eg : 3E11FA47-71CA-11E1-9E33-C80AA9429562:1-5
- 44. How to enable GUID on MySQL replication • Enable read only mode on Slaves set global read_only=1 • Compare the binlog position on master and slave show slave status show master status • Change configuration on all servers and restart bin-log guid_mode=ON Enforce-guid-consistency • Initialize GUID on all servers change master to MASTER_AUTO_POSITION = 1; • Disable read only mode on Slaves
- 51. On Master: [mysqld] rpl_semi_sync_master_enabled=1 rpl_semi_sync_master_timeout=1000 # 1 second On each Slave: [mysqld] rpl_semi_sync_slave_enabled=1
- 52. we need to create the replication user on master mysql> GRANT REPLICATION SLAVE ON *.* TO replication@192.168.1.111 IDENTIFIED BY 'reppwd'; FLUSH PRIVILEGES;
- 53. create Hot backup with * Oracle Enterprise Backup #mysqlbackup --port=3306 --protocol=tcp -- user=root --password --backup-dir=/data/backup backup-and-apply-log * Also can use Percona XtraBackup
- 54. • copy the backup directory to the slave via scp or other method on the master: #tar –cvfZ /data/backup.taz /data/backup #scp /data/backup.taz 192.168.1.111:/data/ on the slave: #tar –xvfZ /data/backup.taz
- 55. • Start the Slave #service start mysql • Start the replication process that will start the io_Thread and the sql_Thread mysql>CHANGE MASTER TO MASTER_HOST='192.168.1.110', MASTER_USER='replication', MASTER_PASSWORD='reppwd', MASTER_AUTO_POSITION=1; START SLAVE;
- 56. show slave statusG *************************** 1. row******** Slave_IO_State: Waiting for master to send event Master_Host: 192.168.1.110 Master_User: replication Master_Log_File: blue-bin.000002 Read_Master_Log_Pos: 936 Relay_Log_File: white-relay-bin.000003 Relay_Log_Pos: 1146 Relay_Master_Log_File: blue-bin.000002 Slave_IO_Running: Yes Slave_SQL_Running: Yes
- 57. show slave statusG *************************** 1. row******** Last_Errno: 0 Last_Error: Skip_Counter: 0 Master_UUID: 2671c08b-7cf0-11e2-ac39-00163ebee7c2 Master_Info_File: mysql.slave_master_info SQL_Delay: 0 SQL_Remaining_Delay: NULL Slave_SQL_Running_State: Slave has read all relay log; waiting for the slave I/O thread to update it Retrieved_Gtid_Set: 2671c08b-7cf0-11e2-ac39-00163ebee7c2:1-4 Executed_Gtid_Set: 2671c08b-7cf0-11e2-ac39-00163ebee7c2:1-4