基于MySQL MEB的备份恢复
MEB（MySQL Enterprise Backup）是MySQL商业版中提供的备份工具，属于物理备份。
同XtraBackup一样，mysqlbackup的使用过程同样包含如下三个步骤：
备份（--backup）=> 应用日志（--apply-log）=> 恢复（--copy-back）
备份
# ./mysqlbackup --backup_dir=/backup --socket=/usr/local/mysql-advanced-5.6.23-linux-glibc2.5-x86_64/data/mysql.sock backup
在备份目录下，会生成以下文件
# ls
backup-my.cnf datadir meta server-all.cnf server-my.cnf
其中datadir和meta是目录，其它是变量配置文件
backup-my.cnf
官方解释如下：
Records the configuration parameters that specify the layout of the MySQL data files.
# cat backup-my.cnf # # Generated backup-my.cnf file. # Auto generated by mysqlbackup program. # [mysqld] innodb_data_file_path=ibdata1:12M:autoextend innodb_log_file_size=50331648 innodb_log_files_in_group=2 innodb_page_size=16384 innodb_checksum_algorithm=innodb
server-all.cnf
该文件记录了备份数据库的所有全局参数
server-my.cnf
该文件记录了备份数据库的非默认的全局参数
注意：在恢复数据库时，可使用server-all.cnf和server-my.cnf中的任意一个。如果需要将数据库恢复到非默认路径，还要修改路径相关的变量值。
再来看看meta目录中的文件
# ls meta/ backup_content.xml backup_create.xml backup_gtid_executed.sql backup_variables.txt MEB_2016-09-27.10-49-21_backup.log
MEB_2016-09-27.10-49-21_backup.log
记录了此次备份的详细信息
backup_content.xml
记录了备份文件的元数据信息和数据库定义信息，同时还记录了备份数据库的plugin信息，恢复时必须确保这些插件在目标数据库中同样存在。
backup_create.xml
记录了备份操作的相关信息，包括备份命令，备份的时间，备份的目录，数据库的参数信息
上述两个文件可通过--disable-manifest选项禁用。
backup_gtid_executed.sql
因为备份数据库启动了GTID复制，故会生成该文件记录GTID的信息
# cat backup_gtid_executed.sql # On a new slave, issue the following command if GTIDs are enabled: SET @@GLOBAL.GTID_PURGED='844e8202-8391-11e6-accb-000c29c64704:1-328944'; # Use the following command if you want to use the GTID handshake protocol: # CHANGE MASTER TO MASTER_AUTO_POSITION=1;
backup_variables.txt
记录了备份的相关信息，该文件由mysqlbackup来控制的，譬如apply_log_done指示是否进行了apply-log操作
# cat backup_variables.txt # # This file is auto generated by mysqlbackup. # [backup_variables] start_lsn=98224128 end_lsn=98227650 apply_log_done=0 is_incremental=0 is_incremental_with_redo_log_only=0 is_partial=0 is_compressed=0 is_skip_unused_pages=0 binlog_position=mysql-bin.000005:65395090 gtid_executed=844e8202-8391-11e6-accb-000c29c64704:1-328944 is_onlyinnodb=0
关于各文件的说明，可参考官方文档的解释
https://dev.mysql.com/doc/mysql-enterprise-backup/3.12/en/meb-files-overview.html
应用日志
./mysqlbackup --backup-dir=/backup/ apply-log
MySQL Enterprise Backup version 3.9.0 [2013/08/23] Copyright (c) 2003, 2013, Oracle and/or its affiliates. All Rights Reserved. mysqlbackup: INFO: Starting with following command line ... ./mysqlbackup --backup-dir=/backup/ apply-log IMPORTANT: Please check that mysqlbackup run completes successfully. At the end of a successful 'apply-log' run mysqlbackup prints "mysqlbackup completed OK!". 160927 11:38:43 mysqlbackup: INFO: MEB logfile created at /backup/meta/MEB_2016-09-27.11-38-43_apply_log.log -------------------------------------------------------------------- Backup Config Options: -------------------------------------------------------------------- datadir = /backup/datadir innodb_data_home_dir = /backup/datadir innodb_data_file_path = ibdata1:12M:autoextend innodb_log_group_home_dir = /backup/datadir innodb_log_files_in_group = 2 innodb_log_file_size = 50331648 innodb_page_size = 16384 innodb_checksum_algorithm = innodb mysqlbackup: INFO: Uses posix_fadvise() for performance optimization. mysqlbackup: INFO: Creating 14 buffers each of size 65536. 160927 11:38:43 mysqlbackup: INFO: Apply-log operation starts with following threads 1 read-threads 1 process-threads 160927 11:38:43 mysqlbackup: INFO: ibbackup_logfile's creation parameters: start lsn 98224128, end lsn 98227650, start checkpoint 98224335. InnoDB: Doing recovery: scanned up to log sequence number 98227650 mysqlbackup: INFO: InnoDB: Starting an apply batch of log records to the database... InnoDB: Progress in percent: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 mysqlbackup: INFO: InnoDB: Setting log file size to 50331648 mysqlbackup: INFO: InnoDB: Setting log file size to 50331648 160927 11:38:48 mysqlbackup: INFO: We were able to parse ibbackup_logfile up to lsn 98227650. mysqlbackup: INFO: Last MySQL binlog file position 0 65394957, file name mysql-bin.000005 160927 11:38:48 mysqlbackup: INFO: The first data file is '/backup/datadir/ibdata1' and the new created log files are at '/backup/datadir' 160927 11:38:48 mysqlbackup: INFO: Apply-log operation completed successfully. 160927 11:38:48 mysqlbackup: INFO: Full backup prepared for recovery successfully. mysqlbackup completed OK!
在应用日志之前，
数据目录中并没有redo log
[root@localhost datadir]# ls
ibbackup_logfile ibdata1 mysql performance_schema test
在应用完日志之后，
数据目录中会生成redo log
[root@localhost datadir]# ls
ibbackup_logfile ibdata1 ib_logfile0 ib_logfile1 mysql performance_schema test
恢复
./mysqlbackup --defaults-file=/backup/server-my.cnf --backup-dir=/backup/ copy-back
./mysqlbackup --defaults-file=/backup/server-my.cnf --backup-dir=/backup/ copy-back MySQL Enterprise Backup version 3.9.0 [2013/08/23] Copyright (c) 2003, 2013, Oracle and/or its affiliates. All Rights Reserved. mysqlbackup: INFO: Starting with following command line ... ./mysqlbackup --defaults-file=/backup/server-my.cnf --backup-dir=/backup/ copy-back IMPORTANT: Please check that mysqlbackup run completes successfully. At the end of a successful 'copy-back' run mysqlbackup prints "mysqlbackup completed OK!". 160927 15:26:55 mysqlbackup: INFO: MEB logfile created at /backup/meta/MEB_2016-09-27.15-26-55_copy_back.log -------------------------------------------------------------------- Server Repository Options: -------------------------------------------------------------------- datadir = /usr/local/mysql-advanced-5.6.23-linux-glibc2.5-x86_64/data/ innodb_data_home_dir = /usr/local/mysql-advanced-5.6.23-linux-glibc2.5-x86_64/data/ innodb_data_file_path = ibdata1:12M:autoextend innodb_log_group_home_dir = /usr/local/mysql-advanced-5.6.23-linux-glibc2.5-x86_64/data/ innodb_log_files_in_group = 2 innodb_log_file_size = 50331648 innodb_page_size = 16384 innodb_checksum_algorithm = innodb innodb_undo_directory = /usr/local/mysql-advanced-5.6.23-linux-glibc2.5-x86_64/data/ innodb_undo_tablespaces = 0 innodb_undo_logs = 128 -------------------------------------------------------------------- Backup Config Options: -------------------------------------------------------------------- datadir = /backup/datadir innodb_data_home_dir = /backup/datadir innodb_data_file_path = ibdata1:12M:autoextend innodb_log_group_home_dir = /backup/datadir innodb_log_files_in_group = 2 innodb_log_file_size = 50331648 innodb_page_size = 16384 innodb_checksum_algorithm = innodb mysqlbackup: INFO: Uses posix_fadvise() for performance optimization. mysqlbackup: INFO: Creating 14 buffers each of size 16777216. 160927 15:26:55 mysqlbackup: INFO: Copy-back operation starts with following threads 1 read-threads 1 write-threads 160927 15:26:55 mysqlbackup: INFO: Copying /backup/datadir/ibdata1 (to '/usr/local/mysql-advanced-5.6.23-linux-glibc2.5-x86_64/data') .160927 15:26:59 mysqlbackup: INFO: Copying /backup/datadir/mysql/innodb_index_stats.ibd. 160927 15:26:59 mysqlbackup: INFO: Copying /backup/datadir/mysql/innodb_table_stats.ibd. 160927 15:26:59 mysqlbackup: INFO: Copying /backup/datadir/mysql/slave_master_info.ibd. 160927 15:26:59 mysqlbackup: INFO: Copying /backup/datadir/mysql/slave_relay_log_info.ibd. 160927 15:26:59 mysqlbackup: INFO: Copying /backup/datadir/mysql/slave_worker_info.ibd. 160927 15:27:00 mysqlbackup: INFO: Copying /backup/datadir/test/test.ibd. 160927 15:27:00 mysqlbackup: INFO: Copying the database directory 'mysql' 160927 15:27:00 mysqlbackup: INFO: Copying the database directory 'performance_schema' 160927 15:27:00 mysqlbackup: INFO: Copying the database directory 'test' 160927 15:27:00 mysqlbackup: INFO: Completing the copy of all non-innodb files. 160927 15:27:00 mysqlbackup: INFO: Copying the log file 'ib_logfile0' 160927 15:27:04 mysqlbackup: INFO: Copying the log file 'ib_logfile1' 160927 15:27:07 mysqlbackup: INFO: Creating server config files server-my.cnf and server-all.cnf in /usr/local/mysql-advanced-5.6.23- linux-glibc2.5-x86_64/data/160927 15:27:07 mysqlbackup: INFO: Copy-back operation completed successfully. 160927 15:27:07 mysqlbackup: INFO: Finished copying backup files to '/usr/local/mysql-advanced-5.6.23-linux-glibc2.5-x86_64/data/' mysqlbackup completed OK!
关于恢复，有以下几点需要注意
1. 恢复必须使用配置文件，建议备份目录下的server-all.cnf和server-my.cnf，事实上，在恢复的过程中，mysqlbackup需要明确上述输出中的参数，譬如，我使用了自己的配置文件进行恢复，结果报如下错误：
# ./mysqlbackup --defaults-file=/usr/local/mysql-advanced-5.6.23-linux-glibc2.5-x86_64/my.cnf --backup-dir=/backup/ copy-backMySQL Enterprise Backup version 3.9.0 [2013/08/23] Copyright (c) 2003, 2013, Oracle and/or its affiliates. All Rights Reserved. mysqlbackup: INFO: Starting with following command line ... ./mysqlbackup --defaults-file=/usr/local/mysql-advanced-5.6.23-linux-glibc2.5-x86_64/my.cnf --backup-dir=/backup/ copy-back IMPORTANT: Please check that mysqlbackup run completes successfully. At the end of a successful 'copy-back' run mysqlbackup prints "mysqlbackup completed OK!". 160927 15:26:09 mysqlbackup: INFO: MEB logfile created at /backup/meta/MEB_2016-09-27.15-26-09_copy_back.log mysqlbackup: ERROR: Server innodb_log_files_in_group is missing or invalid mysqlbackup: ERROR: Server repository configuration problem found. mysqlbackup failed with errors!
很显然，我的配置文件中并没有定义innodb_log_files_in_group参数。
2. 可在上述配置文件中server-all.cnf和server-my.cnf自定义数据目录和base目录，不然默认的都是备份数据库的。
3. 虽然mysqlbackup --help中的解释是：The restore operation assumes the server is offline. Use of this command when server is running is not supported.
但事实上，在server是online的情况下，执行恢复操作并没有报错，甚至还显示“mysqlbackup completed OK!”。但是，并没有覆盖数据目录中的文件。
4. 在启动数据库的过程中，可以使用server-my.cnf或备份数据库的配置文件，不要使用server-all.cnf。在使用server-all.cnf启动数据库的过程中，会报如下错误：
2016-09-27 15:51:37 85229 [ERROR] /usr/local/mysql-advanced-5.6.23-linux-glibc2.5-x86_64/bin/mysqld: Table './mysql/user' is marked a s crashed and should be repaired2016-09-27 15:51:37 85229 [ERROR] Fatal error: Can't open and lock privilege tables: Table './mysql/user' is marked as crashed and sh ould be repaired
这个坑定位了好久，因为server-all.cnf中定义的是所有参数的配置，怀疑跟某些参数有关，因参数较多，时间有限，并没有一一验证。
启动数据库
修改数据目录的权限
# chown -R mysql.mysql /usr/local/mysql-advanced-5.6.23-linux-glibc2.5-x86_64/data
启动数据库
# /usr/local/mysql-advanced-5.6.23-linux-glibc2.5-x86_64/bin/mysqld --defaults-file=/usr/local/mysql-advanced-5.
6.23-linux-glibc2.5-x86_64/my.cnf --user=mysql &
总结
以上只是mysqlbackup的一个简单的备份恢复流程，事实上，mysqlbackup还支持压缩备份等高级特性，后续再表。
