Mysql data directory file description

1. app-server1.err error log file
2. app-server1.pid record mysqld process id, used to lock
3. auto.cnf recording server_uuid database instance mysql, the installation initialization, master and slave is not the same as server_uuid
4.  ib_buffer_pool buffer pool, part of a recent query stored records and indexes, you can view the parameters show variables like 'innodb% pool%'
5. ibdata1 innodb table space, if innodb engine, by default size 10M
6.  ib_logfile0 transaction log file is to ensure that the transaction REDO and UNDO, mainly to ensure that roll forward and roll back the transaction, not to restore with
7. ib_logfile1 transaction log file is to ensure that the transaction REDO and UNDO, not used for restoration
8.  ibtmp1 temporary table space
9. mysql system database directory
10. mysql-bin.000001 binary log files, for recovery, synchronization data from the master
11. mysql-bin.index binary log file indexing, storing binary log file list
12. mysqld_safe.pid storage mysqld_safe script process id
13. performance_schema system database directory
14.  sys system database directory