MySQL simple replication problem: 'show master status' produces 'Empty set'?
I've been setting up MySQL master replication (on Debian 6.0.1) following these instructions faithfully: http://www.neocodesoftware.com/replication/
I've got as far as:
mysql > show master status;
but this is unfortunately producing the following, rather than any useful output:
Empty set (0.00 sec)
The error log at /var/log/mysql.err is just an empty file, so that's not giving me any clues.
Any ideas?
This is what I have put in /etc/mysql/my.cnf on one server (amended appropriately for the other server):
server-id = 1
replicate-same-server-id = 0
auto-increment-increment = 2
auto-increment-offset = 1
master-host = 10.0.0.3
master-user = <myusername>
master-password = <mypass>
master-connect-retry = 60
replicate-do-db = fruit
log-bin = /var/log/mysql-replication.log
binlog-do-db = fruit
And I have set up users and can connect from MySQL on Server A to the database on Server B using the username/password/ipaddress above.
Interestingly, I have mysql running on my PC with binary logs not enabled. I did the following:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 19
Server version: 5.5.12 MySQL Community Server (GPL)
Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> show master status;
Empty set (0.00 sec)
mysql> show binary logs;
ERROR 1381 (HY000): You are not using binary logging
mysql>
As shown, since MySQL shows "Empty Set" for SHOW MASTER STATUS; because binary logging was not enabled. That's obvious given the configuration I have.
First thing you should do is make sure the error log has a specific folder
[mysqld]
log-error=/var/log/mysql/mysql.err
log-bin = /var/log/mysql/mysql-replication.log
Then run the following:
service mysql stop
mkdir /var/log/mysql
chown -R mysql:mysql /var/log/mysql
service mysql start
Then in the mysql client run these SQL Commands
SHOW MASTER STATUS;
SHOW BINARY LOGS;
If you get the same output I had before, then MySQL cannot write binary logs to the designated folder. Your dilemma becomes why MySQL cannot write to /var/log.
This is not a full answer but I hope this helps.
If thhe Mysql version is >5.0, your replication settings master-host, master-user, master-password and a few others in your my.cnf will be ignored. Use CHANGE MASTER TO for initial replication setup.
Compare http://dev.mysql.com/doc/refman/5.1/en/replication-howto-slaveinit.html