Preparing a Full Backup with innobackupex¶
The purpose of the prepare stage is to perform any pending operations and make the data consistent. After creating a backup, for example, uncommitted transactions must be undone or log transactions must be replayed. After this stage has finished, the data is ready.
To prepare a backup with innobackupex you have to use the
innobackupex --apply-log option and full path to the backup directory as an
argument:
$ innobackupex --apply-log /path/to/BACKUP-DIR
and check the last line of the output for a confirmation on the process:
150806 01:01:57 InnoDB: Shutdown completed; log sequence number 1609228
150806 01:01:57 innobackupex: completed OK!
If it succeeded, innobackupex performed all operations needed, leaving the data ready to use immediately.
Under the hood¶
innobackupex started the prepare process by reading the configuration from the
backup-my.cnf file in the backup directory.
After that, innobackupex replayed the committed transactions in the log files (some transactions could have been done while the backup was being done) and rolled back the uncommitted ones. Once this is done, all the information lay in the tablespace (the InnoDB files), and the log files are re-created.
This implies calling innobackupex --apply-log twice. More details of
this process are shown in the xtrabackup section.
Note that this preparation is not suited for incremental backups. If you perform it on the base of an incremental backup, you will not be able to “add” the increments. See Incremental Backups with innobackupex.
Other options to consider¶
innobackupex --use-memory¶
The preparing process can be sped up by using more memory in it. It depends on
the free or available RAM on your system, it defaults to 100MB. In
general, the more memory available to the process, the better. The amount of
memory used in the process can be specified by multiples of bytes:
$ innobackupex --apply-log --use-memory=4G /path/to/BACKUP-DIR