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The guide assumes that you have SSH access to the server Squirro servers and the password to access mysql passwords.

  1. Identify the current master

  2. For each broken slave, stop the Squirro cluster service:


    $ sudo monit stop sqclusterd


  3. Ensure you have a running system with one cluster node.

  4. At the master:


    mysql> RESET MASTER;
    Query OK, 0 rows affected (0.14 sec)
     
    mysql> FLUSH TABLES WITH READ LOCK;
    Query OK, 0 rows affected (0.00 sec)
     
    mysql> SHOW MASTER STATUS;
    +------------------+----------+--------------+------------------+
    | File             | Position | Binlog_Do_DB | Binlog_Ignore_DB |
    +------------------+----------+--------------+------------------+
    | mysql-bin.000001 |     12268 |              |                  |
    +------------------+----------+--------------+------------------+
    1 row in set (0.00 sec)
     
    mysql>
     
     
    $ mkdir /var/lib/squirro/cluster/mysql/<date>
    $ mysqldump --host=127.0.0.1 --port=3306 --user=cluster --password=$(PASSWORD) --all-databases --master-data --single-transaction --result-file /var/lib/squirro/cluster/mysql/<date>/dump.db
     
    $ mysql -u root -p
    mysql> UNLOCK TABLES;
     
    $ cd /var/lib/squirro/cluster/mysql/<date>/
    $ gzip dump.db
    $ scp dump.db.gz $(SSH_USER)@$(IP_SLAVE1):/tmp/
    $ scp dump.db.gz $(SSH_USER)@$(IP_SLAVE2):/tmp/


  5. On each slave:


    $ mkdir /var/lib/squirro/cluster/mysql/restore-<date>
    $ mv /tmp/dump.db.gz /var/lib/squirro/cluster/mysql/restore-<date>
    $ cd /var/lib/squirro/cluster/mysql/restore-<date>
    $ gunzip dump.db.gz
     
    mysql> stop slave;
     
    $ mysql --host=127.0.0.1 --port=3306 --user=cluster --password=$(PASSWORD) -e "source dump.db;"
    $ mysql -u root -p
    mysql> RESET SLAVE;
    mysql> change master to master_user='repl';
    mysql> show slave status\G;    --> if master_host does not point to current master, e.g.: mysql> change master to master_host = "$(IP_MASTER)";
     
    mysql> CHANGE MASTER TO MASTER_LOG_FILE='mysql-bin.000001', MASTER_LOG_POS=12268;            --> ensure that the position matches the value from SHOW MASTER STATUS; above
    mysql> START SLAVE;
    mysql> show slave status\G;      --> ensure that Slave_IO_Running: Yes  and   Slave_SQL_Running: Yes
     
    $ monit start sqclusterd
    $ monit summary