Create a full backup¶
To create a backup, run xtrabackup with the --backup
option. You also need to specify the --target-dir option, which is where
the backup will be stored, if the InnoDB data or log files are not stored
in
the same directory, you might need to specify the location of those, too.
If the
target directory does not exist, xtrabackup creates it. If the directory
does
exist and is empty, xtrabackup will succeed.
xtrabackup will not overwrite existing files, it will fail with operating
system error 17, file exists.
To start the backup process run:
$ xtrabackup --backup --target-dir=/data/backups/
This will store the backup at /data/backups/. If you specify a
relative path, the target directory will be relative to the current directory.
During the backup process, you should see a lot of output showing the data
files being copied, as well as the log file thread repeatedly scanning the
log files and copying from it. Here is an example that shows the log thread
scanning the log in the background, and a file copying thread working on the ibdata1 file:
Expected output
160906 10:19:17 Finished backing up non-InnoDB tables and files
160906 10:19:17 Executing FLUSH NO_WRITE_TO_BINLOG ENGINE LOGS...
xtrabackup: The latest check point (for incremental): '62988944'
xtrabackup: Stopping log copying thread.
.160906 10:19:18 >> log scanned up to (137343534)
160906 10:19:18 Executing UNLOCK TABLES
160906 10:19:18 All tables unlocked
160906 10:19:18 Backup created in directory '/data/backups/'
160906 10:19:18 [00] Writing backup-my.cnf
160906 10:19:18 [00] ...done
160906 10:19:18 [00] Writing xtrabackup_info
160906 10:19:18 [00] ...done
xtrabackup: Transaction log of lsn (26970807) to (137343534) was copied.
160906 10:19:18 completed OK!
The last thing you should see is something like the following, where the
value of the <LSN> will be a number that depends on your system:
$ xtrabackup: Transaction log of lsn (<LSN>) to (<LSN>) was copied.
Note
Log copying thread checks the transactional log every second to see if there were any new log records written that need to be copied, but there is a chance that the log copying thread might not be able to keep up with the amount of writes that go to the transactional logs, and will hit an error when the log records are overwritten before they could be read.
After the backup is finished, the target directory will contain files such as the following, assuming you have a single InnoDB table test.tbl1 and you are using MySQL’s innodb_file_per_table option:
$ ls -lh /data/backups/
The result should look like this:
Expected output
total 182M
drwx------ 7 root root 4.0K Sep 6 10:19 .
drwxrwxrwt 11 root root 4.0K Sep 6 11:05 ..
-rw-r----- 1 root root 387 Sep 6 10:19 backup-my.cnf
-rw-r----- 1 root root 76M Sep 6 10:19 ibdata1
drwx------ 2 root root 4.0K Sep 6 10:19 mysql
drwx------ 2 root root 4.0K Sep 6 10:19 performance_schema
drwx------ 2 root root 4.0K Sep 6 10:19 sbtest
drwx------ 2 root root 4.0K Sep 6 10:19 test
drwx------ 2 root root 4.0K Sep 6 10:19 world2
-rw-r----- 1 root root 116 Sep 6 10:19 xtrabackup_checkpoints
-rw-r----- 1 root root 433 Sep 6 10:19 xtrabackup_info
-rw-r----- 1 root root 106M Sep 6 10:19 xtrabackup_logfile
The backup can take a long time, depending on how large the database is. It is safe to cancel at any time, because xtrabackup does not modify the database.
The next step is to prepare the backup in order to restore it.
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