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备份还原：RMAN还原离奇的慢

huangtingzhong 发布于 2025-06-22 21:35BACKUP & RESTORE抢沙发

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下面的场景来自于一个朋友在客户现场反馈的一个备份工程师还原的问题，在某客户现场还原一套数据库的耗时比预期长了很多，使得耗时远超计划。因为备份与还原是由其它的备份工程师在操作，在数据库这块不是他的强项，采用了能还原但是不是最优的还原方案，出现了还原数据库速度慢的现象。其实我们知道，RMAN备份与还原也是可以通过配置参数来提到性能，如果是通过备份软件，还可以通过调用备份软件的BUFFER来实现，多路复用等机制来优化，如果数据文件存放在ASM环境中，现在ORACLE可以自动优化RMAN相关的ORACLE参数，对参与人员技术要求越来越低。然后，这次同事遇到的RMAN还原慢的主要原因不是由于RMAN配置的导致的，而是采用的逐个数据文件还原导致的，下面我们通过模拟要证明，是什么原因导致整个备份速度慢。

这里将备份集存放在磁盘上，没有模拟磁带的情况。

1，环境介绍

www.htz.pw > select * from v$version;

BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
PL/SQL Release 11.2.0.3.0 - Production
CORE    11.2.0.3.0      Production
TNS for 64-bit Windows: Version 11.2.0.3.0 - Production
NLSRTL Version 11.2.0.3.0 - Production
www.htz.pw > host uname -a
windows32 luoping 2.6.1 7601 i686-pc Intel unknown MinGW

2，测试数据创建

这里创建了多个表空间，用于模拟生产环境

1，创建多个表空间

.............
create tablespace htz25 datafile 'D:\APP\LUOPING\ORADATA\HTZ\HTZ25.DBF' size 10M;

创建测试表

....................
create table htz.htz25 tablespace htz25 as select * from dba_objects;

3,配置归档

Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup mount;
ORACLE instance started.

Total System Global Area  392495104 bytes
Fixed Size                  2255544 bytes
Variable Size             155190600 bytes
Database Buffers          226492416 bytes
Redo Buffers                8556544 bytes
Database mounted.
SQL> alter database archivelog;
Database altered.
SQL> alter database open;
Database altered.

4，配置备份脚本

由于备份脚本的内容太多，就不贴出来了，只贴了rman的命令

ALLOCATE CHANNEL ch00 TYPE DISK;
ALLOCATE CHANNEL ch01 TYPE DISK;
BACKUP
      INCREMENTAL Level=0
      FORMAT 'd:\shell\bk_u%u_s%s_p%p_t%t'
      DATABASE;
sql 'alter system archive log current';
RELEASE CHANNEL ch00;
RELEASE CHANNEL ch01;
# Backup all archive logs
ALLOCATE CHANNEL ch00 TYPE DISK;
BACKUP
      FILESPERSET 20
      FORMAT 'd:\shell\arch-s%s-p%p-t%t'
      ARCHIVELOG ALL;
RELEASE CHANNEL ch00;
ALLOCATE CHANNEL ch00 TYPE DISK;
BACKUP
      FORMAT 'd:\shell\cntrl_p_t'
      CURRENT CONTROLFILE;
RELEASE CHANNEL ch00;
}

d:\shell>hot_database.cmd
RMAN> 2> 3> 4> 5> 6> 7> 8> 9> 10> 11> 12> 13> 14> 15> 16> 17> 18> 19> 20> 21> 22> 23> RMAN> LOGMSGDATERMAN_LOG_FILE

rman备份日志输出内容

Script name: hot_database.cmd 

Recovery Manager: Release 11.2.0.3.0 - Production on Sun Sep 21 23:53:06 2014

Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.

connected to target database: HTZ (DBID=1913545637)
using target database control file instead of recovery catalog

RMAN> 2> 3> 4> 5> 6> 7> 8> 9> 10> 11> 12> 13> 14> 15> 16> 17> 18> 19> 20> 21> 22> 23> 
allocated channel: ch00
channel ch00: SID=134 device type=DISK

allocated channel: ch01
channel ch01: SID=199 device type=DISK

Starting backup at 2014-09-21:23:53:07
channel ch00: starting incremental level 0 datafile backup set
channel ch00: specifying datafile(s) in backup set
input datafile file number=00001 name=D:\APP\LUOPING\ORADATA\HTZ\SYSTEM01.DBF
input datafile file number=00012 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ08.DBF
input datafile file number=00014 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ10.DBF
input datafile file number=00016 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ12.DBF
input datafile file number=00018 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ14.DBF
input datafile file number=00020 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ16.DBF
input datafile file number=00022 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ18.DBF
input datafile file number=00023 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ19.DBF
input datafile file number=00024 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ20.DBF
input datafile file number=00025 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ21.DBF
input datafile file number=00026 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ22.DBF
input datafile file number=00027 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ23.DBF
input datafile file number=00028 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ24.DBF
input datafile file number=00029 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ25.DBF
channel ch00: starting piece 1 at 2014-09-21:23:53:07
channel ch01: starting incremental level 0 datafile backup set
channel ch01: specifying datafile(s) in backup set
input datafile file number=00002 name=D:\APP\LUOPING\ORADATA\HTZ\SYSAUX01.DBF
input datafile file number=00003 name=D:\APP\LUOPING\ORADATA\HTZ\UNDOTBS01.DBF
input datafile file number=00004 name=D:\APP\LUOPING\ORADATA\HTZ\USERS01.DBF
input datafile file number=00005 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ01.DBF
input datafile file number=00006 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ02.DBF
input datafile file number=00007 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ03.DBF
input datafile file number=00008 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ04.DBF
input datafile file number=00009 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ05.DBF
input datafile file number=00010 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ06.DBF
input datafile file number=00011 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ07.DBF
input datafile file number=00013 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ09.DBF
input datafile file number=00015 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ11.DBF
input datafile file number=00017 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ13.DBF
input datafile file number=00019 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ15.DBF
input datafile file number=00021 name=D:\APP\LUOPING\ORADATA\HTZ\HTZ17.DBF
channel ch01: starting piece 1 at 2014-09-21:23:53:08
channel ch00: finished piece 1 at 2014-09-21:23:53:23
piece handle=D:\SHELL\BK_U0FPJ3JF3_S15_P1_T858901987 tag=TAG20140921T235307 comment=NONE
channel ch00: backup set complete, elapsed time: 00:00:16
channel ch00: starting incremental level 0 datafile backup set
channel ch00: specifying datafile(s) in backup set
channel ch01: finished piece 1 at 2014-09-21:23:53:23
piece handle=D:\SHELL\BK_U0GPJ3JF3_S16_P1_T858901987 tag=TAG20140921T235307 comment=NONE
channel ch01: backup set complete, elapsed time: 00:00:15
channel ch01: starting incremental level 0 datafile backup set
channel ch01: specifying datafile(s) in backup set
including current SPFILE in backup set
channel ch01: starting piece 1 at 2014-09-21:23:53:23
including current control file in backup set
channel ch00: starting piece 1 at 2014-09-21:23:53:24
channel ch01: finished piece 1 at 2014-09-21:23:53:24
piece handle=D:\SHELL\BK_U0IPJ3JFJ_S18_P1_T858902003 tag=TAG20140921T235307 comment=NONE
channel ch01: backup set complete, elapsed time: 00:00:01
channel ch00: finished piece 1 at 2014-09-21:23:53:25
piece handle=D:\SHELL\BK_U0HPJ3JFJ_S17_P1_T858902003 tag=TAG20140921T235307 comment=NONE
channel ch00: backup set complete, elapsed time: 00:00:01
Finished backup at 2014-09-21:23:53:25
通过日志，可以看到生成了2个备份片的信息
5，还原测试
同样由于还原脚本内容太多，这里只贴了还原命令
5.1 备份工程师还原脚本模拟
RUN {
ALLOCATE CHANNEL ch00 TYPE DISK;
ALLOCATE CHANNEL ch01 TYPE DISK;
RESTORE DATAFILE 1 ;
RESTORE DATAFILE 2 ;
RESTORE DATAFILE 3 ;
RESTORE DATAFILE 4 ;
RESTORE DATAFILE 5 ;
RESTORE DATAFILE 6 ;
RESTORE DATAFILE 7 ;
RESTORE DATAFILE 8 ;
RESTORE DATAFILE 9 ;
RESTORE DATAFILE 10;
RESTORE DATAFILE 11;
RESTORE DATAFILE 12;
RESTORE DATAFILE 13;
RESTORE DATAFILE 14;
RESTORE DATAFILE 15;
RESTORE DATAFILE 16;
RESTORE DATAFILE 17;
RESTORE DATAFILE 18;
RESTORE DATAFILE 19;
RESTORE DATAFILE 20;
RESTORE DATAFILE 21;
RESTORE DATAFILE 22;
RESTORE DATAFILE 23;
RESTORE DATAFILE 24;
RESTORE DATAFILE 25;
RESTORE DATAFILE 26;
RESTORE DATAFILE 27;
RESTORE DATAFILE 28;   
RESTORE DATAFILE 29;  
RELEASE CHANNEL ch00;
RELEASE CHANNEL ch01;
}
d:\shell>restore.cmd                                                                                                                                               
RMAN> 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> RMAN> LOGMSGDATERMAN_LOG_FILE

这里可以看到，每个数据文件都是一个单独的restore来还原。
下面来看看生成的日志内容

Script name: restore.cmd 

Recovery Manager: Release 11.2.0.3.0 - Production on Sun Sep 21 23:59:14 2014

Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.

connected to target database: HTZ (DBID=1913545637, not open)
using target database control file instead of recovery catalog

RMAN> 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> 
allocated channel: ch00
channel ch00: SID=129 device type=DISK

allocated channel: ch01
channel ch01: SID=192 device type=DISK

Starting restore at 2014-09-21:23:59:15

channel ch00: starting datafile backup set restore
channel ch00: specifying datafile(s) to restore from backup set
channel ch00: restoring datafile 00001 to D:\APP\LUOPING\ORADATA\HTZ\SYSTEM01.DBF
channel ch00: reading from backup piece D:\SHELL\BK_U0FPJ3JF3_S15_P1_T858901987
channel ch00: piece handle=D:\SHELL\BK_U0FPJ3JF3_S15_P1_T858901987 tag=TAG20140921T235307
channel ch00: restored backup piece 1
channel ch00: restore complete, elapsed time: 00:00:07
Finished restore at 2014-09-21:23:59:23

......
channel ch00: starting datafile backup set restore
channel ch00: specifying datafile(s) to restore from backup set
channel ch00: restoring datafile 00007 to D:\APP\LUOPING\ORADATA\HTZ\HTZ03.DBF
channel ch00: reading from backup piece D:\SHELL\BK_U0GPJ3JF3_S16_P1_T858901987
channel ch00: piece handle=D:\SHELL\BK_U0GPJ3JF3_S16_P1_T858901987 tag=TAG20140921T235307
channel ch00: restored backup piece 1
channel ch00: restore complete, elapsed time: 00:00:01
Finished restore at 2014-09-21:23:59:32

Starting restore at 2014-09-21:23:59:32

channel ch00: starting datafile backup set restore
channel ch00: specifying datafile(s) to restore from backup set
channel ch00: restoring datafile 00008 to D:\APP\LUOPING\ORADATA\HTZ\HTZ04.DBF
channel ch00: reading from backup piece D:\SHELL\BK_U0GPJ3JF3_S16_P1_T858901987
channel ch00: piece handle=D:\SHELL\BK_U0GPJ3JF3_S16_P1_T858901987 tag=TAG20140921T235307
channel ch00: restored backup piece 1
channel ch00: restore complete, elapsed time: 00:00:01
Finished restore at 2014-09-21:23:59:33

Starting restore at 2014-09-21:23:59:33

channel ch00: starting datafile backup set restore
channel ch00: specifying datafile(s) to restore from backup set
channel ch00: restoring datafile 00009 to D:\APP\LUOPING\ORADATA\HTZ\HTZ05.DBF
channel ch00: reading from backup piece D:\SHELL\BK_U0GPJ3JF3_S16_P1_T858901987
channel ch00: piece handle=D:\SHELL\BK_U0GPJ3JF3_S16_P1_T858901987 tag=TAG20140921T235307
channel ch00: restored backup piece 1
channel ch00: restore complete, elapsed time: 00:00:01
Finished restore at 2014-09-21:23:59:34

Starting restore at 2014-09-21:23:59:34

channel ch00: starting datafile backup set restore
channel ch00: specifying datafile(s) to restore from backup set
channel ch00: restoring datafile 00010 to D:\APP\LUOPING\ORADATA\HTZ\HTZ06.DBF
channel ch00: reading from backup piece D:\SHELL\BK_U0GPJ3JF3_S16_P1_T858901987
channel ch00: piece handle=D:\SHELL\BK_U0GPJ3JF3_S16_P1_T858901987 tag=TAG20140921T235307
channel ch00: restored backup piece 1
channel ch00: restore complete, elapsed time: 00:00:01
Finished restore at 2014-09-21:23:59:35

Starting restore at 2014-09-21:23:59:35

channel ch00: starting datafile backup set restore
channel ch00: specifying datafile(s) to restore from backup set
channel ch00: restoring datafile 00011 to D:\APP\LUOPING\ORADATA\HTZ\HTZ07.DBF
channel ch00: reading from backup piece D:\SHELL\BK_U0GPJ3JF3_S16_P1_T858901987
channel ch00: piece handle=D:\SHELL\BK_U0GPJ3JF3_S16_P1_T858901987 tag=TAG20140921T235307
channel ch00: restored backup piece 1
channel ch00: restore complete, elapsed time: 00:00:01
Finished restore at 2014-09-21:23:59:36

Starting restore at 2014-09-21:23:59:36

channel ch00: starting datafile backup set restore
channel ch00: specifying datafile(s) to restore from backup set
channel ch00: restoring datafile 00012 to D:\APP\LUOPING\ORADATA\HTZ\HTZ08.DBF
channel ch00: reading from backup piece D:\SHELL\BK_U0FPJ3JF3_S15_P1_T858901987
channel ch00: piece handle=D:\SHELL\BK_U0FPJ3JF3_S15_P1_T858901987 tag=TAG20140921T235307
channel ch00: restored backup piece 1
channel ch00: restore complete, elapsed time: 00:00:01
Finished restore at 2014-09-21:23:59:37

Starting restore at 2014-09-21:23:59:37

channel ch00: starting datafile backup set restore
channel ch00: specifying datafile(s) to restore from backup set
channel ch00: restoring datafile 00013 to D:\APP\LUOPING\ORADATA\HTZ\HTZ09.DBF
channel ch00: reading from backup piece D:\SHELL\BK_U0GPJ3JF3_S16_P1_T858901987
channel ch00: piece handle=D:\SHELL\BK_U0GPJ3JF3_S16_P1_T858901987 tag=TAG20140921T235307
channel ch00: restored backup piece 1
channel ch00: restore complete, elapsed time: 00:00:01
Finished restore at 2014-09-21:23:59:39

Starting restore at 2014-09-21:23:59:39

channel ch00: starting datafile backup set restore
channel ch00: specifying datafile(s) to restore from backup set
channel ch00: restoring datafile 00014 to D:\APP\LUOPING\ORADATA\HTZ\HTZ10.DBF
channel ch00: reading from backup piece D:\SHELL\BK_U0FPJ3JF3_S15_P1_T858901987
channel ch00: piece handle=D:\SHELL\BK_U0FPJ3JF3_S15_P1_T858901987 tag=TAG20140921T235307
channel ch00: restored backup piece 1
channel ch00: restore complete, elapsed time: 00:00:01
Finished restore at 2014-09-21:23:59:40

Starting restore at 2014-09-21:23:59:40

channel ch00: starting datafile backup set restore
channel ch00: specifying datafile(s) to restore from backup set
channel ch00: restoring datafile 00015 to D:\APP\LUOPING\ORADATA\HTZ\HTZ11.DBF
channel ch00: reading from backup piece D:\SHELL\BK_U0GPJ3JF3_S16_P1_T858901987
channel ch00: piece handle=D:\SHELL\BK_U0GPJ3JF3_S16_P1_T858901987 tag=TAG20140921T235307
channel ch00: restored backup piece 1
channel ch00: restore complete, elapsed time: 00:00:01
Finished restore at 2014-09-21:23:59:41
.......................
其中一个备份片来看
channel ch00: reading from backup piece D:\SHELL\BK_U0FPJ3JF3_S15_P1_T858901987
channel ch00: reading from backup piece D:\SHELL\BK_U0FPJ3JF3_S15_P1_T858901987
channel ch00: reading from backup piece D:\SHELL\BK_U0FPJ3JF3_S15_P1_T858901987
channel ch00: reading from backup piece D:\SHELL\BK_U0FPJ3JF3_S15_P1_T858901987
channel ch00: reading from backup piece D:\SHELL\BK_U0FPJ3JF3_S15_P1_T858901987
channel ch00: reading from backup piece D:\SHELL\BK_U0FPJ3JF3_S15_P1_T858901987
channel ch00: reading from backup piece D:\SHELL\BK_U0FPJ3JF3_S15_P1_T858901987
channel ch00: reading from backup piece D:\SHELL\BK_U0FPJ3JF3_S15_P1_T858901987
channel ch00: reading from backup piece D:\SHELL\BK_U0FPJ3JF3_S15_P1_T858901987
channel ch00: reading from backup piece D:\SHELL\BK_U0FPJ3JF3_S15_P1_T858901987
channel ch00: reading from backup piece D:\SHELL\BK_U0FPJ3JF3_S15_P1_T858901987
channel ch00: reading from backup piece D:\SHELL\BK_U0FPJ3JF3_S15_P1_T858901987
channel ch00: reading from backup piece D:\SHELL\BK_U0FPJ3JF3_S15_P1_T858901987
channel ch00: reading from backup piece D:\SHELL\BK_U0FPJ3JF3_S15_P1_T858901987
在整个还原中，读了这么多次备份片，因为每一个restore命令就会去读还原片的信息，这就是慢的原因所在了。特别是在生产环境中，都是备份到磁带中的，还原不慢才怪。  
下面计算一下还原的时间
Starting restore at 2014-09-21:23:59:15
Finished restore at 2014-09-21:23:59:57
第一次还原使用了42S的时间，因为BUFFER的影响，多次测试，时间都差不多。
5.2 使用一条命令来还原
RUN {
ALLOCATE CHANNEL ch00 TYPE DISK;
ALLOCATE CHANNEL ch01 TYPE DISK;
RESTORE DATABASE; 
RELEASE CHANNEL ch00;
RELEASE CHANNEL ch01;
}
d:\shell>restore.cmd
RMAN> 2> 3> 4> 5> 6> 7> RMAN> LOGMSGDATERMAN_LOG_FILE

后台日志内容如下：


Recovery Manager: Release 11.2.0.3.0 - Production on Mon Sep 22 00:06:23 2014

Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.

connected to target database: HTZ (DBID=1913545637, not open)
using target database control file instead of recovery catalog

RMAN> 2> 3> 4> 5> 6> 7> 
allocated channel: ch00
channel ch00: SID=129 device type=DISK

allocated channel: ch01
channel ch01: SID=191 device type=DISK

Starting restore at 2014-09-22:00:06:24

………………..
还原的时间，每一次测试

Finished restore at 2014-09-22:00:36:07

第二次测试

Finished restore at 2014-09-22:00:37:23

这里看到两次的时间都不到20S，远远小于之前的时间。

6，实验总结

在做rman还原的时候，尽量把命令写在一个restore命令中，减少对相同备份片进行重复的读取工作。另外整个实验需要注意的是：没有考虑一个数据文件写到一个备份片的情况。

——————作者介绍———————–
姓名：黄廷忠
现就职：Oracle中国高级服务团队
曾就职：OceanBase、云和恩墨、东方龙马等
电话、微信、QQ：18081072613
个人博客: (http://www.htz.pw)
CSDN地址: (https://blog.csdn.net/wwwhtzpw)
博客园地址: (https://www.cnblogs.com/www-htz-pw)

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