[Warning] innodb_mirrored_log_groups is an unimplemented feature and the
variable will be completely rem oved in a future version.
refs similar 5.7 branch update:
874af6de
# these are actual defaults (as of 5.0.26)
innodb_data_home_dir = @clusterdir@/mysqldb/db
innodb_data_file_path = ibdata1:10M:autoextend
-innodb_mirrored_log_groups=1
innodb_log_group_home_dir = @clusterdir@/mysqldb/db
innodb_log_files_in_group=2
innodb_log_file_size=5M