The InnoDB-related data files that are backed up include the ibdata* files (which represent the system tablespace and possibly the data for some user tables), any .ibd files (which contains data from user tables created with the file-per-table setting enabled), and the data extracted from the ib_logfile* files (the redo log information representing changes that occur while the backup is running), which is stored in a new backup file ibbackup_logfile.
If you use the compressed backup feature, the
.ibd files are renamed in their compressed
form to .ibz files.
The files, as they are originally copied, form a
raw backup that
requires further processing before it is ready to be restored.
You then run the apply step
(either as part of a
copy-back-and-apply-log command or a
command, or as a separate
apply-log command), which
updates the backup files based on the changes recorded in the
ibbackup_logfile file, producing a
backup. At this point, the backup data corresponds to a
single point in time. The files are now ready to be restored, or
for some other uses such as testing, reporting, or deployment as
a replication slave.
To restore InnoDB tables to their original state, you must also
have the corresponding .frm
files along with the backup data. Otherwise, the table
definitions could be missing or outdated if someone has run
ALTER TABLE or
statements since the backup. By default,
mysqlbackup automatically copies the
.frm files during a backup operation and
restores the files during a restore operation.