[Log] how many logs in MySQL

redo redo logs
  Role: To ensure durability of transactions, to prevent failure, not dirty pages are written to disk. Restart the database will be executed redo log redo reach transactional consistency
  
undo the rollback log
  Action: to ensure the atomicity of data, a version of the data recorded before the transaction occurred, for rollback.
  repeatable read and read innodb transaction isolation level that has been submitted by mvcc + undo achieve 

errorlog error log
  Role: Mysql itself to start, stop, error messages occur during operation
  
slow query log slow query log
  Role: record execution time is too long sql, time threshold can be configured to record only successful execution

binlog binary log
  Action: a master-slave replication for master-slave synchronization
  
relay log relay logs
  Action: a master-slave synchronization database, the primary database will be transmitted first binlog stored locally, and playback from library
  
general log normal log 
  action: database records details of operation, is disabled by default, open will reduce database performance