/home/travis/server/bin/mariabackup based on MariaDB server 10.4.2-MariaDB Linux (x86_64) 
mariabackup: cd to /home/travis/logs/vardir/backup/
Loading encryption plugin from file_key_management=file_key_management
Loading encryption plugin
	 Encryption plugin parameter :  '--plugin_load=file_key_management=file_key_management'
	 Encryption plugin parameter :  '--file_key_management_encryption_algorithm=aes_cbc'
	 Encryption plugin parameter :  '--file_key_management_filekey='
	 Encryption plugin parameter :  '--file_key_management_filename=/home/travis/mariadb-toolbox/data/keys.txt'
	 Encryption plugin parameter :  '--prepare'
	 Encryption plugin parameter :  '--target-dir=/home/travis/logs/vardir/backup/'
	 Encryption plugin parameter :  '--user=root'
mariabackup: This target seems to be not prepared yet.
mariabackup: using the following InnoDB configuration for recovery:
mariabackup:   innodb_data_home_dir = .
mariabackup:   innodb_data_file_path = ibdata1:12M:autoextend
mariabackup:   innodb_log_group_home_dir = .
2019-01-09 11:18:34 0x7f86d3a46740 InnoDB: Using Linux native AIO
mariabackup: Starting InnoDB instance for recovery.
mariabackup: Using 104857600 bytes for buffer pool (set by --use-memory parameter)
2019-01-09 11:18:34 0 [Note] InnoDB: !!!!!!!! UNIV_DEBUG switched on !!!!!!!!!
2019-01-09 11:18:34 0 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2019-01-09 11:18:34 0 [Note] InnoDB: Uses event mutexes
2019-01-09 11:18:34 0 [Note] InnoDB: Compressed tables use zlib 1.2.8
2019-01-09 11:18:34 0 [Note] InnoDB: Number of pools: 1
2019-01-09 11:18:34 0 [Note] InnoDB: Using SSE2 crc32 instructions
/home/travis/server/bin/mariabackup: O_TMPFILE is not supported on /tmp (disabling future attempts)
2019-01-09 11:18:34 0 [Note] InnoDB: Initializing buffer pool, total size = 100M, instances = 1, chunk size = 100M
2019-01-09 11:18:34 0 [Note] InnoDB: Completed initialization of buffer pool
2019-01-09 11:18:34 0 [Note] InnoDB: If the mysqld execution user is authorized, page cleaner thread priority can be changed. See the man page of setpriority().
2019-01-09 11:18:34 0 [Note] InnoDB: Starting crash recovery from checkpoint LSN=143154
Last binlog file , position 0
190109 11:18:35 completed OK!