Data Directory Files in MySQL.

The MySQL Server consists of below files...

1. mysql
2. peformance_schema
3. test
4. iblogfile0
5. iblogfile1
6. ibdata1

mysql

This database consists of tables which are related to mysql's users, time which are associated to mysql installed on the server.

test

This is a test database. This can be deleted if the DBA doesn't want.

iblogfile0 & iblogfile1

These are the log files on the Mysql Server Data directory. when ever any user enter the data / any operations that are performed on the innodb_buffer_pool & from there it comes to iblogfile0 & iblogfile1. After some checkpoints the data is committed to the disk.

ibdata1

ibdata1 is the table space data file and its log files.

If innodb is not specified then mysql creates an auto_extending data file slightly longer than 100MB