Hi all,
I need to document the switch between master and slave
and I want to double check if the outlined procedure is correct.
We have a simple master slave replication setup on OEL 5.5 and MySQL
5.5.13.
Original config: machineA master, machineB slave.
Target: machineB master, machineA not operational.
On the master:
1. flush logs on the master (only if it's accessible, of course).
On the slave:
2. stop slave io_thread
3. Wait until show processlist reports "Has read all relay log".
4. stop slave
5. reset master
6. change master to master_host='' and reset slave (only to be sure that
the slave couldn't be started easily by mistake)
7. Start the application and checK if everything's OK
Now I should have only machineB operational,
I don't care for the state of machineA at this point.
To restore the initial state: machineA master, machineB slave:
1. Stop the application (assuming that's not a problem).
2. Generate a consistent dump on machineB:
mysqldump -u username -ppassword -A -x > dump_file
3. Import on machineA
mysql -u username -ppassword < dump_file
4. On machineA after the import:
reset master;
change master to master_host=''; # just in case, I prefer to have all
info reset for safety
reset slave; # see above
flush tables with read lock; # just in case, because there
are no connections but mine at this time
show master status; # just in case, it should
be 4, right after the reset master command
5. On machineB (the slave):
change master to
master_host='machineA',
master_user='<my_rep_usr>',
master_password='<password>',
master_log_file='mysql-bin.000001',
master_log_pos=<pos>;
master_log_file and master_log_pos should be unnecessary because after
the reset master they should correspond to the default values
of change master command, but again, it's just for safety.
Am I missing something?
Best regards
Dimitre
