前言
在xtrabackup使用的过程中，主要会有以下几个文件生成，本文就这几个文件的内容以及作用进行记录和说明。
xtrabackup_binlog_info xtrabackup_binlog_pos_innodb xtrabackup_checkpoints xtrabackup_info xtrabackup_logfile xtrabackup_slave_info backup-my.cnf
实验过程
master [localhost] {msandbox} ((none)) > show master status\G
*************************** 1. row ***************************
File: mysql-bin.000011
Position: 1549
Binlog_Do_DB:
Binlog_Ignore_DB:
Executed_Gtid_Set:
1 row in set (0.00 sec)
master [localhost] {msandbox} (test) > insert into test values(1,'zhangsan');
Query OK, 1 row affected (0.04 sec)
master [localhost] {msandbox} (test) > insert into test values(2,'lisi');
Query OK, 1 row affected (0.04 sec)
master [localhost] {msandbox} ((none)) > show master status\G
*************************** 1. row ***************************
File: mysql-bin.000011
Position: 2140
Binlog_Do_DB:
Binlog_Ignore_DB:
Executed_Gtid_Set:
1 row in set (0.00 sec)
innobackupex --socket=/tmp/mysql_sandbox21489.sock \ --user=msandbox \ --password=msandbox \ --no-timestamp \ --slave-info \ /data/full
170305 21:24:27 innobackupex: Starting the backup operation
IMPORTANT: Please check that the backup run completes successfully.
At the end of a successful backup run innobackupex
prints "completed OK!".
....
xtrabackup: using the following InnoDB configuration:
xtrabackup: innodb_data_home_dir = ./
xtrabackup: innodb_data_file_path = ibdata1:12M:autoextend
xtrabackup: innodb_log_group_home_dir = ./
xtrabackup: innodb_log_files_in_group = 2
xtrabackup: innodb_log_file_size = 50331648
# 这里的信息会被记录到backup-my.cnf 文件中，backup-my.cnf 是启动备份集所需要的最小参数。
....
xtrabackup: Transaction log of lsn (2142985143) to (2142987473) was copied.
# 我们可以看到我们当时插入的数据的redo log已经被拷贝
170305 21:24:33 completed OK!
master [localhost] {msandbox} (test) > show engine innodb status\G
....
---
LOG
---
Log sequence number 2142987473
Log flushed up to 2142987473
Pages flushed up to 2142987473
Last checkpoint at 2142987473
Max checkpoint age 80826164
Checkpoint age target 78300347
...
[root@COS-DEV-MySQL full]# cat xtrabackup_binlog_info mysql-bin.000011 2140
[root@COS-DEV-MySQL full]# cat xtrabackup_checkpoints backup_type = full-backuped from_lsn = 0 # 由于是全量备份，所以数据是从LSN=0开始的 to_lsn = 2142987473 last_lsn = 2142987473 compact = 0 recover_binlog_info = 0
[root@COS-DEV-MySQL full]# cat xtrabackup_info uuid = 231d9d80-01a9-11e7-bcb1-080027a1fd1c name = tool_name = innobackupex tool_command = --socket=/tmp/mysql_sandbox21489.sock --user=msandbox --password=... --no-timestamp --slave-info /data/full tool_version = 2.3.7 ibbackup_version = 2.3.7 server_version = 5.6.24-72.2-log start_time = 2017-03-05 21:39:14 end_time = 2017-03-05 21:39:20 lock_time = 0 binlog_pos = filename 'mysql-bin.000011', position '2140' innodb_from_lsn = 0 innodb_to_lsn = 2142987473 partial = N incremental = N format = file compact = N compressed = N encrypted = N
[root@COS-DEV-MySQL full]# innobackupex --apply-log . 170305 21:42:17 innobackupex: Starting the apply-log operation ... InnoDB: Shutdown completed; log sequence number 2142991038 170305 21:42:21 completed OK!
[root@COS-DEV-MySQL full]# cat xtrabackup_binlog_pos_innodb mysql-bin.000011 2140 [root@COS-DEV-MySQL full]# cat xtrabackup_binlog_info mysql-bin.000011 2140
master [localhost] {msandbox} (test) > show create table test_myisam\G
*************************** 1. row ***************************
Table: test_myisam
Create Table: CREATE TABLE `test_myisam` (
`id` int(11) DEFAULT NULL,
`name` varchar(10) DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1
1 row in set (0.00 sec)
master [localhost] {msandbox} (test) > insert into test_myisam values(2,'aa');
Query OK, 1 row affected (0.00 sec)
....
master [localhost] {msandbox} (test) > show master status\G
*************************** 1. row ***************************
File: mysql-bin.000011
Position: 3120
Binlog_Do_DB:
Binlog_Ignore_DB:
Executed_Gtid_Set:
1 row in set (0.00 sec)
[root@COS-DEV-MySQL master]# innobackupex --socket=/tmp/mysql_sandbox21489.sock \
> --user=msandbox \
> --password=msandbox \
> --no-timestamp \
> --slave-info \
> /data/full2
170305 22:07:42 innobackupex: Starting the backup operation
IMPORTANT: Please check that the backup run completes successfully.
At the end of a successful backup run innobackupex
prints "completed OK!".
MySQL binlog position: filename 'mysql-bin.000011', position '3120'
170305 22:07:49 [00] Writing backup-my.cnf
170305 22:07:49 [00] ...done
170305 22:07:49 [00] Writing xtrabackup_info
170305 22:07:49 [00] ...done
xtrabackup: Transaction log of lsn (2142987473) to (2142987473) was copied.
# 我们发现myisam表由于是非事务型存储引擎，中间的事务日志没有产生，因此没有产生redo拷贝
# 此时只有xtrabackup_binlog_info文件生成，没有xtrabackup_binlog_pos_innodb
[root@COS-DEV-MySQL full2]# cat xtrabackup_binlog_info
mysql-bin.000011 3120
[root@COS-DEV-MySQL full2]# innobackupex --apply-log .
....
InnoDB: Starting shutdown...
InnoDB: Shutdown completed; log sequence number 2142990651
170305 22:08:39 completed OK!
[root@COS-DEV-MySQL full2]# cat xtrabackup_binlog_pos_innodb
mysql-bin.000011 2140
[root@COS-DEV-MySQL full2]# cat xtrabackup_binlog_info
mysql-bin.000011 3120
# 我们发现xtrabackup_binlog_pos_innodb中的位置和xtrabackup_binlog_info不一样，因为xtrabackup_binlog_pos_innodb只是记录innodb和xtradb的binlog位点，myisam产生的binlog不会计算在内，因此xtrabackup_binlog_pos_innodb的信息和第一次全备的xtrabackup_binlog_info文件中的信息是一致的。
所以如果存在多种存储引擎，需要利用xtrabackup_binlog_info 来确定备份的完成那个时刻的binlog位点。
[root@COS-DEV-MySQL full]# cat xtrabackup_checkpoints backup_type = full-prepared from_lsn = 0 to_lsn = 2142987473 last_lsn = 2142987473 compact = 0 recover_binlog_info = 0
slave1 [localhost] {msandbox} ((none)) > show slave status\G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 127.0.0.1
Master_User: rsandbox
Master_Port: 21489
Connect_Retry: 60
Master_Log_File: mysql-bin.000011
Read_Master_Log_Pos: 3120
# slave1 和主库是实时同步，位点为11号binlog的3120位点。
slave1 [localhost] {msandbox} ((none)) > show master status\G
*************************** 1. row ***************************
File: mysql-bin.000007
Position: 120
# 此时的slave的 binlog位点
[root@COS-DEV-MySQL full_slave]# cat xtrabackup_binlog_info mysql-bin.000007 120 # xtrabackup_binlog_info 记录的是从库的binlog位点。 [root@COS-DEV-MySQL full_slave]# [root@COS-DEV-MySQL full_slave]# cat xtrabackup_slave_info CHANGE MASTER TO MASTER_LOG_FILE='mysql-bin.000011', MASTER_LOG_POS=3120 # 发现xtrabackup_slave_info记录的是主库的binlog信息，该信息可以用来通过从库创建一个从库，然后指向主库！非常棒！该信息需要在备份的时候加上 --slave-info .
小结
在工作中，突然对某个文件的意义有点不大明确，导致差点踩坑，好尴尬????
通过实验明确了各个文件的含义，防止犯错。
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