Mysql Pn Replication Gtid Failover

MySQL 5.6 Replication: Self-Healing Clusters with GTIDs

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Overview

PART 1

  Fail-over Base –  Global Transaction Identifiers –  Automatic Positioning –  Hands-On

PART 2   Under the Hood – Become a GTID Expert

–  How Slave Preserves GTIDs –  GTIDs Must Be Unique

  Integration With Other Features –  Seeking & Skipping: Empty Transactions –  Purging Binary Logs –  Provisioning a Slave From a Backup


Fail-over  Crash can happen to anyone:

–  Hardware failure –  Human mistake –  Bug –  Natural disaster

 Automatic fail-over with Global Transaction Identifiers: –  Reduces admin overhead –  Prevents planned downtime –  Prevents unplanned downtime

Introduction to MySQL Replication Fail-over Base Under the Hood Integration With Other Features


Fail-over  Handle server crash with minimal disruption

 Example 1: tree

C

B

A



Fail-over  Handle server crash with minimal disruption

 Example 1: tree

C

B

A Crash



Fail-over

C

B

A

 Handle server crash with minimal disruption

 Example 1: tree



Fail-over

C

B

A

Make B the new master


 Example 1: tree



Fail-over

C A B


 Example 1: tree

 Example 2: line



Fail-over

C A B Crash


 Example 1: tree

 Example 2: line



Fail-over

C A B


 Example 1: tree

 Example 2: line



Fail-over

C A B

Make A direct master of C


 Example 1: tree

 Example 2: line



Fail-over

C

A

B

D


 Example 1: tree

 Example 2: line

 Example 3: circle



Fail-over

C

A

B

D Crash


 Example 1: tree

 Example 2: line




Fail-over

C

A

B

D


 Example 1: tree

 Example 2: line




Fail-over

C

A

Make a shortcut in the circle

B

D


 Example 1: tree

 Example 2: line




Fail-over

C

A

B

D


 Example 1: tree

 Example 2: line


 Example 4: scheduled maintenance



Fail-over

C

A

B

D

Take out D!


 Example 1: tree

 Example 2: line





Fail-over

C

A

B

D

Maintain D offline, without

disrupting service


 Example 1: tree

 Example 2: line





Fail-over

C

A

B

D


 Example 1: tree

 Example 2: line






 Example 1: tree

 Example 2: line



 Example 5: arbitrary topology

Fail-over

A

B C

D

E

F




Wow! I really want to get started

with fail-over. Tell me more!


Overview

  Introduction to MySQL Replication   Fail-over Base

–  Global Transaction Identifiers –  Automatic Positioning –  Hands-On

  Under the Hood – Become a GTID Expert –  How Slave Preserves GTIDs –  GTIDs Must Be Unique



Global Transaction Identifiers  Server assigns Global Transaction Identifier (GTID) to every

transaction: –  server_uuid:number

a61678ba-4889-4279-9e58-45ba840af334:1 –  server_uuid identifies the server; globally unique –  number is incremented by 1 for each transaction on this server






 Writes GTID to binary log






 Writes GTID to binary log  Slave ensures transaction gets the same GTID when re-executed



Global Transaction Identifiers master> CREATE TABLE t1 (a INT); master> SELECT @@global.gtid_executed; a61678ba-4889-4279-9e58-45ba840af334:1 master> INSERT INTO t1 VALUES (1); master> INSERT INTO t1 VALUES (2); master> SELECT @@global.gtid_executed; a61678ba-4889-4279-9e58-45ba840af334:1-3


Note: interval

New variable: gtid_executed


Global Transaction Identifiers master> SELECT @@global.gtid_executed; a61678ba-4889-4279-9e58-45ba840af334:1-10000 slave> SELECT @@global.gtid_executed; a61678ba-4889-4279-9e58-45ba840af334:1-9999



Global Transaction Identifiers master> SELECT @@global.gtid_executed; a61678ba-4889-4279-9e58-45ba840af334:1-10000 slave> SELECT @@global.gtid_executed; a61678ba-4889-4279-9e58-45ba840af334:1-9999


Slave is missing one transaction Slave is missing one transaction



OK, I get it. So we have GTIDs.

How are they used in fail-over?


Overview






Automatic Positioning  Example 1: tree

A

(crashed) (master)

A id1,trx1, id2,trx2, id3,trx3

(slave)

C id1,trx1 (slave)

id1,trx1, id2,trx2 B




A

(crashed) (master)


(slave)

C id1,trx1 Crash! (slave)





(slave)

C id1,trx1 (slave)


A

(crashed) (crashed)


id1

id2, trx2,...


What the slave has

What the slave does not have


Automatic Positioning  Example 1: tree  Example 2: circle

B A C

client client




id1,trx1 B A C

client client trx1





id2,trx2 A C

client client trx2 trx1




id1,trx1, id2,trx2, id3,trx3

B id2,trx2

A C

client client trx2 trx1, trx3





B id2,trx2

A C


Crash!





B id2,trx2

A C


id2 id1,trx1,id3,trx3,...


What the slave has

What the slave does not have



Awesome! I'm really eager to get started.

How do I set it up?


Overview






Hands-On  Prerequisites:

–  Use transactional storage engine for all tables (InnoDB) –  Don't use CREATE TABLE … SELECT –  Don't execute CREATE TEMPORARY TABLE or

DROP TEMPORARY TABLE inside a transaction



Hands-On  Prepare the server for fail-over

1. Sync and stop all servers 2. Add to every my.cnf:

gtid-mode=on enforce-gtid-consistency=on log-bin log-slave-updates

3. Start all servers 4. Execute: > CHANGE MASTER TO MASTER_AUTO_POSITION = 1



Hands-On  Perform fail-over

On the slave, simply point to the new master: > CHANGE MASTER TO MASTER_HOST = '<host>', MASTER_PORT = <port number>, MASTER_USER = '<user name>' MASTER_PASSWORD = 'secret';

  No positions needed!




C

B

A CHANGE MASTER TO MASTER_HOST = 'B', MASTER_PORT = <B's port>, MASTER_USER = '<user name>' MASTER_PASSWORD = 'secret';




CHANGE MASTER TO MASTER_HOST = 'A', MASTER_PORT = <A's port>, MASTER_USER = '<user name>' MASTER_PASSWORD = 'secret'; C

A

B

D



Next Steps

  More on GTIDs –  svenmysql.blogspot.co.uk

  More on MySQL 5.6 Replication –  http://dev.mysql.com/tech-resources/articles/

mysql-5.6-replication.html

  Try Out MySQL 5.6RC –  http://dev.mysql.com/downloads/mysql/

Mysql Pn Replication Gtid Failover

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