Daisy Chain Replication Setup

Daisy chain Replication configuration is very complex and should only be attempted by users who are experienced with replication. Incorrect setup can result in corrupt data, computer crashes, or other serious consequences. For a one-way replication configuration, see One-Way Replication Setup.

Note:

Instructions

MySQL comes with its own replication capabilities. Make sure to use Statement Based Replication, and NOT Row Based Replication.

  1. Add servers and designate a slave monitor. See Replication: Add Servers and Designate a Slave Monitor

    You must have a Slave Monitor when running Daisy Chain Replication. The Slave Monitor will immediately notify all users and IT staff if replication crashes. We are not responsible for the damage done when databases continue to be used after an error crashes replication.

  2. Stop the MySQL service on all replication servers (net stop mysql). On some operating systems, this will require you go into the system services in Control Panel, Administrative Tools, Services and stop the MySQL service manually. If the MySQL service is started on any replication server before step 5, then replication will fail.
  3. On all replication servers, wipe out all loose files in the mysql data directory which do not reside in a subfolder, except for any files beginning with ib (e.g. iblog_file0, ib_logfile1, ibdata1).
  4. Make an identical database copy on all replication servers. The replicated database must be exactly the same on all replication servers before replication begins the first time.
  5. On all replications servers, set autoincrement / offset variables in the my.ini file. Do this before going to the next step. See Replication: Setting Auto Increment / Offset Variables.
  6. Make sure all the servers are synced to the same date and time. If locations are in different timezones, data will be synced but may not show at all locations.
  7. Start the MySQL service on all replication servers (net start mysql). On some operating systems, such as Windows Vista, this will require you go into the system services in Control Panel, Administrative Tools, Services and start the MySQL service manually.
  8. Set each replication server's master server by running a command similar to the following (run the following MySQL queries):

    Go the command line and change the directory to C:\Program Files\MySQL\MySQL Server 5.5\bin and type the following: mysql -u root opendental where opendentalis the name of the database.

    CHANGE MASTER TO

    MASTER_HOST = 'MASTER_OF_THIS_SERVER',

    MASTER_USER = 'repl',

    MASTER_PASSWORD = 'od1234';

    Set MASTER_HOST to either the IP address or computer name of the replication master of this server. We recommend IP address to reduce possible DNS issues

  9. For each replication server, run the following queries to grant permission for any replication slave to read data.

    GRANT CREATE TEMPORARY TABLES ON opendental.* TO 'repl' IDENTIFIED BY 'od1234';

    GRANT SUPER ON *.* TO 'repl' IDENTIFIED BY 'od1234';

    GRANT REPLICATION SLAVE ON *.* TO 'repl' IDENTIFIED BY 'od1234';

    The opendental.* should be the name of your mysql database and must be lowercase. The .* means everything within the specified database.

  10. Run the START SLAVE; in the mysql command interface for each replication server in the chain.
  11. Run the SHOW SLAVE STATUS\G; in the mysql command interface for each replication server in the chain. Make sure that the Slave IO Running and Slave SQL Running columns both say, Yes.
  12. How to test replication between two replication servers. Only test two replication servers at a time. We recommend testing the first replication server in the chain with the last replication server in the chain. If the test fails, make several smaller tests between consecutive replication servers.
    • From server1, run the following SQL to create a junk temporary table: CREATE TABLE tmp123 (Col1 VARCHAR(1));
    • From server2, verify that table tmp123 was created by running the following SQL: SELECT * FROM tmp123;
    • From server2, run the following SQL to create a junk temporary table: CREATE TABLE tmp456 (Col1 VARCHAR(1));
    • From server1, verify that table tmp456 was created by running the following SQL: SELECT * FROM tmp456;
    • From server1, delete table tmp456 by running the following SQL: DROP TABLE tmp456;
    • From server2, verify that table tmp456 was dropped by running the following SQL and verifying that tmp456 does NOT show up: SHOW TABLES LIKE 'tmp456%';
    • From server2, delete table tmp123 by running the following SQL: DROP TABLE tmp123;
    • From server1, verify that table tmp123 was dropped by running the following SQL and verifying that tmp123 does NOT show up: SHOW TABLES LIKE 'tmp123%';

Server_1 IP 192.168.0.1database=databasename Server_2 IP 192.168.0.2database=databasename

Check the log files to make sure the files were created and time stamps are recent. C:\mysql\data

C:\mysql\data>dir

02/22/2008 01:25 PM 57 relay-log.info

02/22/2008 09:12 PM 235 server-relay-bin.000043

02/22/2008 09:12 PM 26 server-relay-bin.index

02/22/2008 01:22 PM 17,642 server.err

02/22/2008 01:22 PM 5 server.pid

C:\mysql\data>dir\

02/22/2008 01:25 PM 57 relay-log.info

02/22/2008 09:12 PM 235 server-relay-bin.000043

02/22/2008 09:12 PM 26 server-relay-bin.index

02/22/2008 01:22 PM 17,642 server.err

02/22/2008 01:22 PM 5 server.pid