PerconaXtraBackup --全备增备prepare restore

Xtrabackup

Xtrabackup包含两个主要的工具,即xtrabackup和innobackupex,二者区别如下:
• xtrabackup只能备份innodb和xtradb引擎表,而不能备份MyISAM表
• innobackupex是一个封装了xtrabackup的Perl脚本,支持同时备份innodb和MyISAM,但在对MyISAM备份时需要加一个全局的读锁

创建用户赋予权限

CREATE USER 'backup'@'localhost' IDENTIFIED BY 'backup';
GRANT RELOAD, LOCK TABLES, REPLICATION CLIENT,PROCESS ON *.* TO 'backup'@'localhost';

innobackupex调用xtrabackup备份xtradb和innodb,调用perl脚本备份MyISAM表

创建完整备份示例

innobackupex --defaults-file=/data/mysqldata/3306/my.cnf --user=backup --password='backup'/data/mysqldata/backup/

如果使用–defaults-file选项,则必须在第一位

备份完成后会在目录下创建一个以时间命名的目录

[mysql@master backup]$ pwd
/data/mysqldata/backup
[mysql@master backup]$ ls
2016-08-18_18-23-33

–no-timestamp 该选项告诉innobackupex不创建一个时间戳目录存储备份

innobackupex --defaults-file=/data/mysqldata/3306/my.cnf --user=backup --password='backup'--no-timestamp /data/mysqldata/backup/base

上例中备份会存放在base目录下,如果目录不存在会自动创建

创建备份后并不能直接用于恢复.需要先prepare.

prepare的目的是跑一下redo,将未提交的rollback,回滚的回滚,跑出一个一致性的备份

innobackupex --apply-log /data/mysqldata/backup/base/

查看输出的最后一行 completed OK!表示prepare成功

prepare前

backup-my.cnf ibdata1 performance_schema test xtrabackup_checkpoints xtrabackup_logfile
fandb mysql sakila xtrabackup_binlog_info xtrabackup_info

prepare后

backup-my.cnf ib_logfile0 ibtmp1 sakila xtrabackup_binlog_pos_innodb xtrabackup_logfile
fandb ib_logfile1 mysql test xtrabackup_checkpoints
ibdata1 ib_logfile2 performance_schema xtrabackup_binlog_info xtrabackup_info

ib_logfile0,1,2由prepare生成

–use-memory 使用此参数可以提升prepare速度,默认100M

innobackupex --apply-log --use-memory=4G/data/mysqldata/backup/base/

restore全备

为了方便,innobackupex有一个–copy-back选项,可以将备份拷贝回datadir下

innobackupex --defaults-file=/data/mysqldata/3306/my.cnf --copy-back /data/mysqldata/backup/base

datadir必须是空的,除非使用了–force-non-empty-directories 参数.MySQL在copy-back时应该是关闭的

如果创建备份时使用的是其他OS用户,那么在copy-back后你应该修改权限

chown -R mysql:mysql

增量备份(增量只针对xtradb和innodb引擎,其他引擎表仍是全备)

增量备份之前必须有一个全备份.

innobackupex --defaults-file=/data/mysqldata/3306/my.cnf --user=backup --password='backup'--no-timestamp /data/mysqldata/backup/base
备份成功后,会生成一个文件xtrabackup_checkpoints
[mysql@master backup]$ more base/xtrabackup_checkpoints
backup_type = full-backuped
from_lsn =0
to_lsn =143682470
last_lsn =143682470
compact =0
recover_binlog_info =0

使用上面的全备做为基础,做增量备份

innobackupex --defaults-file=/data/mysqldata/3306/my.cnf --user=backup --password='backup'--no-timestamp --incremental /data/mysqldata/backup/incr1 --incremental-basedir=/data/mysqldata/backup/base
备份成功后,查看增备的xtrabackup_checkpoints
[mysql@master backup]$ more incr1/xtrabackup_checkpoints
backup_type = incremental
from_lsn =143682470
to_lsn =143683016
last_lsn =143683016
compact =0
recover_binlog_info =0

再次创建一个增量备份,将以刚才的增备作为基础

innobackupex --defaults-file=/data/mysqldata/3306/my.cnf --user=backup --password='backup'--no-timestamp --incremental /data/mysqldata/backup/incr2 --incremental-basedir=/data/mysqldata/backup/incr1
[mysql@master backup]$ more incr2/xtrabackup_checkpoints
backup_type = incremental
from_lsn =143683016
to_lsn =143683562
last_lsn =143683562
compact =0
recover_binlog_info =0
增倍时应该是要读取base的xtrabackup_checkpoints文件,从该文件的last_lsn开始备份.
于是我手动创建一个目录incr3,并创建一个文件xtrabackup_checkpoints,以此作为base也是可以备份的.
将该xtrabackup_checkpoints文件的last_lsn改为0也可以,但仍不是全备
手动指定lsn,也可以成功创建增量备份.这种方法适用于当base不可用时
innobackupex --defaults-file=/data/mysqldata/3306/my.cnf --user=backup --password='backup'--incremental /data/mysqldata/backup/incr1 --incremental-lsn=143680036

–incremental-lsn=name
This option specifies the log sequence number (LSN) to
use for the incremental backup. The option accepts a
string argument. It is used with the –incremental
option. It is used instead of specifying
–incremental-basedir. For databases created by MySQL and
Percona Server 5.0-series versions, specify the LSN as
two 32-bit integers in high:low format. For databases
created in 5.1 and later, specify the LSN as a single
64-bit integer.

prepare增备

prepare增量备份与prepare全备稍有不同

• First, only the committed transactions must be replayed on each backup. This will merge the base full backup with the incremental ones.
• Then, the uncommitted transaction must be rolled back in order to have a ready-to-use backup.
1.首先,在所有备份重演提交的事务,这会合并增量备份和全备
2.所有未提交事务回滚

恢复基础备份(全备)这里一定要加–redo-only参数,该参数意思是只应用xtrabackup日志中已经提交的事务数据,不回滚还未提交的数据

innobackupex --apply-log --redo-only /data/mysqldata/backup/base/

将增量备份incr应用到基础备份base

innobackupex --apply-log --redo-only /data/mysqldata/backup/base/--incremental-dir=/data/mysqldata/backup/incr1

将增量备份incr2应用到基础备份base,注意恢复最后一个增量备份时需要去掉–redo-only参数,回滚xtrabackup日志中那些还未提交的数据

innobackupex --apply-log /data/mysqldata/backup/base/--incremental-dir=/data/mysqldata/backup/incr2

Note: –redo-only should be used when merging all incrementals except the last one. That’s why the previous
line doesn’t contain the –redo-only option. Even if the –redo-only was used on the last step, backup would still be consistent but in that case server would perform the rollback phase.
–redo-only只在最后一个增备时不使用.如果在最后一个增倍时使用了–redo-only,备份仍是一致的,但在这种情况下，服务器将执行回滚阶段

要注意的是,prepare应该按照备份的时间顺序,即全备-增备1-增备2-增备3…
如果顺序错误,备份将不可用.如果你不知道正确的熟顺序,可以查看xtrabackup_checkpoints文件

把所有合在一起的基础备份整体进行一次apply操作,回滚未提交的数据

innobackupex --apply-log /data/mysqldata/backup/base/

这一步是可选的,如果你不做,MySQL会去回滚未提交的数据.同时,因为iblog文件不会被备份,这一步也会创建它们,如果不做这一步,MySQL启动时也会创建它们.

copy-back

innobackupex --defaults-file=/data/mysqldata/3306/my.cnf --copy-back --rsync /data/mysqldata/backup/base

–rsync Uses the rsync utility to optimize local file transfers.
When this option is specified, innobackupex uses rsync to
copy all non-InnoDB files instead of spawning a separate
cp for each file, which can be much faster for servers
with a large number of databases or tables. This option
cannot be used together with –stream.