Topology refactoring using classic MySQL replication commands – version 1

A week ago I wrote a post about promoting a mysql slave as master. Today I will write topology refactoring using classic replication commands. Context: Initial state: dbfoo1(M) – dbfoo2(MS) – dbrfoo3(S) Desired state: dbfoo1(M) – dbfoo2(S) \ dbfoo3(S) Let’s get to work: stop slave on dbfoo3 MariaDB [(none)]> stop slave; check the “freezing point” … Continue reading Topology refactoring using classic MySQL replication commands – version 1

Relay log read failure: Could not parse relay log event entry

It happened today… why? Well, I was testing parallel replication (slave_parallel_threads) and after setting the number of threads to zero and when started the slave I got this wonderful error message: MariaDB [(none)]> show slave status\G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: master.example.com Master_User: user Master_Port: 3306 Connect_Retry: 60 … Continue reading Relay log read failure: Could not parse relay log event entry

How to fix “ERROR: Connecting to daemon at /var/run/collectd-unixsock failed”

Sometimes connecting to the collectd unixsocket is not possible giving a connection refused. This can be fixed manually by removing manually the socket file and then restart collectd collectd does not create a new socket file when there is already such a file. But the old file, which is not connected to any process certainly … Continue reading How to fix “ERROR: Connecting to daemon at /var/run/collectd-unixsock failed”

mysql: preload InnoDB buffer pool

Why?! To avoid a lengthy warmup period after restarting the server, particularly for instances with large InnoDB buffer pools. Things to be added to /etc/mysq/my.cnf: # Shortened warm-up times with a preloaded InnoDB buffer pool innodb_buffer_pool_dump_at_shutdown=ON innodb_buffer_pool_load_at_startup=ON Basically when MySQL receives the TERM signal will dump the InnoDB buffer pool /data/db/mysql/ib_buffer_pool and it will load it … Continue reading mysql: preload InnoDB buffer pool