MAXPIECESIZE与FORMAT参数设置不合理导致RMAN备份失败 / 憋错料

今天去客户那里搭建DG，当创建RMAN备份集的时候，遇到了个问题，导致备份集始终无法生成，由于客户的备份集为10G左右，一次备份就要一个多小时，开始浪费了不少时间，诊断后发现，原来问题出在MAXPIECESIZE上，下面自己做了个测试，来说明这个故障现象和解决方法：

[[email protected] ~]# su - oracle

[[email protected] ~]$ sqlplus / as sysdba

SQL*Plus: Release 10.2.0.1.0 - Production on 24 14:32:34 2014

Connected to:

Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production

With the Partitioning, OLAP and Data Mining options

SQL> select open_mode from v$database;

OPEN_MODE

----------

READ WRITE

SQL> exit

Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production

With the Partitioning, OLAP and Data Mining options

[[email protected] ~]$ rman target /

Recovery Manager: Release 10.2.0.1.0 - Production on 24 14:32:52 2014

connected to target database: ORA10G (DBID=4175411955)

RMAN> show all;

using target database control file instead of recovery catalog

RMAN configuration parameters are:

CONFIGURE RETENTION POLICY TO REDUNDANCY 5;

CONFIGURE BACKUP OPTIMIZATION ON;

CONFIGURE DEFAULT DEVICE TYPE TO DISK;

CONFIGURE CONTROLFILE AUTOBACKUP ON;

CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO ‘/u01/orabackup/backupsets/ora10g-%F.ctl‘;

CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET;

CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default

CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default

CONFIGURE CHANNEL DEVICE TYPE DISK MAXPIECESIZE 10000 M; --最大备份集限制

CONFIGURE MAXSETSIZE TO UNLIMITED; # default

CONFIGURE ENCRYPTION FOR DATABASE OFF; # default

CONFIGURE ENCRYPTION ALGORITHM ‘AES128‘; # default

CONFIGURE ARCHIVELOG DELETION POLICY TO NONE;

CONFIGURE SNAPSHOT CONTROLFILE NAME TO ‘/u01/app/oracle/product/10.2.0/db_1/dbs/snapcf_ora10g.f‘; # default

RMAN> exit

Recovery Manager complete.

[[email protected] ~]$ cd /u01/orabackup/scripts/

[[email protected] scripts]$ ls -l

total 4

-rwxr-xr-x 1 oracle oinstall 2443 Dec 24 14:29 backup_full.sh

[[email protected] scripts]$ ./backup_full.sh

RMAN> RMAN> RMAN> RMAN> RMAN> RMAN> RMAN> RMAN> RMAN> RMAN> 2> 3> RMAN> RMAN> RMAN> RMAN> [[email protected] backupsets]$ ls -lrth

total 190M

-rw-r----- 1 oracle oinstall 9.8M Dec 24 14:24 ora10g-4175411955_20141224_867162246_380.arc

-rw-r----- 1 oracle oinstall 1.7M Dec 24 14:24 ora10g-4175411955_20141224_867162255_381.arc

-rw-r----- 1 oracle oinstall 439K Dec 24 14:24 ora10g-4175411955_20141224_867162257_382.arc

-rw-r----- 1 oracle oinstall 747K Dec 24 14:33 ora10g-4175411955_20141224_867162820_384.arc

-rw-r----- 1 oracle oinstall 170M Dec 24 14:36 ora10g-4175411955_20141224_867162823_385.db

-rw-r----- 1 oracle oinstall 491K Dec 24 14:36 ora10g-4175411955_20141224_867162990_386.arc

-rw-r----- 1 oracle oinstall 7.3M Dec 24 14:36 ora10g-c-4175411955-20141224-00.ctl

[[email protected] backupsets]$

根据刚才的配置，正确的生成了RMAN备份集，总大小为190M左右，其中最大的数据文件的备份集为170M，而在RMAN脚本中配置的

在备份脚本中，配置了format格式为“$ORACLE_SID-%I_%T_%t_%s.db”，以下为脚本具体的语句：

backup as compressed backupset database format ‘$RMAN_BACKUPSETS/$ORACLE_SID-%I_%T_%t_%s.db‘ tag ‘db_bak‘ plus archivelog
format ‘$RMAN_BACKUPSETS/$ORACLE_SID-%I_%T_%t_%s.arc‘ not backed up 1 times delete all input tag ‘arc_bak‘;

当把MAXPIECESIZE的值改小，比之前最大的备份集大小（170M）还要小，比方说改成100M后，再运行之前的备份脚本，然后查看RMAN输出的日志文件，发现报ORA-27038，提示文件已经存在：

[[email protected] backupsets]$ cat ../logs/rman.log |grep ORA-

ORA-19504: failed to create file "/u01/orabackup/backupsets/ora10g-4175411955_20141224_867163196_389.db"

ORA-27038: created file already exists

channel ORA_DISK_1: starting piece 2 at 2014-12-24

RMAN-00571: ===========================================================

RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============

RMAN-00571: ===========================================================

RMAN-03002: failure of backup plus archivelog command at 12/24/2014 14:41:52

ORA-19504: failed to create file "/u01/orabackup/backupsets/ora10g-4175411955_20141224_867163196_389.db"

ORA-27038: created file already exists

Additional information: 1

正常情况下，生成的最大备份集有170M，但是刚才通过修改MAXPIECESIZE参数为100M后，在生成备份集时，一旦备份集大小超过100M时，就会自动生成第2个备份片，而由于我在format中仅仅是配置了“$ORACLE_SID-%I_%T_%t_%s.db”，这几个通配符的含义是：

%I -- DBID

%T -- 日期时间（年月日）

%t -- 自动生成的时间戳

%s -- 备份集序列号（Sequence）

当第一个备份片达到MAXPIECESIZE限定的100M后，想去生成第2个文件，但是由于这几个通配符不足以区分备份集中的备份片（生成了同一个文件名），当第2个备份片创建时提示文件已存在，最终导致备份失败。

解决这个问题的方法有2种：

1. 在format参数中增加%p通配符

当超过MAXPIECESIZE后，只有%p才能够生成不同的备份片，因为%t这个时间戳不足以区分不同的别分片的名称

[[email protected] backupsets]$ . ../scripts/backup_full.sh

RMAN> RMAN> RMAN> RMAN> RMAN> RMAN> RMAN> RMAN> RMAN> RMAN> 2> 3> RMAN> RMAN> RMAN> RMAN> [[email protected] backupsets]$ ls -lrth ../backupsets/

total 375M

-rw-r----- 1 oracle oinstall 9.8M Dec 24 14:24 ora10g-4175411955_20141224_867162246_380.arc

-rw-r----- 1 oracle oinstall 1.7M Dec 24 14:24 ora10g-4175411955_20141224_867162255_381.arc

-rw-r----- 1 oracle oinstall 439K Dec 24 14:24 ora10g-4175411955_20141224_867162257_382.arc

-rw-r----- 1 oracle oinstall 747K Dec 24 14:33 ora10g-4175411955_20141224_867162820_384.arc

-rw-r----- 1 oracle oinstall 170M Dec 24 14:36 ora10g-4175411955_20141224_867162823_385.db

-rw-r----- 1 oracle oinstall 491K Dec 24 14:36 ora10g-4175411955_20141224_867162990_386.arc

-rw-r----- 1 oracle oinstall 7.3M Dec 24 14:36 ora10g-c-4175411955-20141224-00.ctl

-rw-r----- 1 oracle oinstall 30K Dec 24 14:39 ora10g-4175411955_20141224_867163193_388.arc

-rw-r----- 1 oracle oinstall 7.4M Dec 24 15:03 ora10g-4175411955_20141224_867164604_390_1.arc

-rw-r----- 1 oracle oinstall 99M Dec 24 15:05 ora10g-4175411955_20141224_867164614_391_1.db

-rw-r----- 1 oracle oinstall 73M Dec 24 15:06 ora10g-4175411955_20141224_867164614_391_2.db

-rw-r----- 1 oracle oinstall 22K Dec 24 15:06 ora10g-4175411955_20141224_867164776_392_1.arc

-rw-r----- 1 oracle oinstall 7.3M Dec 24 15:06 ora10g-c-4175411955-20141224-01.ctl

[[email protected] backupsets]$

在format中增加%p通配符后，问题得到解决，通过脚本备份集又可以正常创建备份集了，注意由于配置了%p，这里db的备份集变成了2个备份片，分别为“_1”，“_2”，以100M为分割点（MAXPIECESIZE指定的大小）

[[email protected] backupsets]$ cat ../logs/rman.log |grep ORA-

ORA-19504: failed to create file "/u01/orabackup/backupsets/ora10g-4175411955_20141224_867163196_389.db"

ORA-27038: created file already exists

[[email protected] backupsets]$

由于RMAN备份日志用的是append方式，抓取出来的这个错误时之前记录进去的，没有新增的ORA-27038出现了

2. 将MAXPIECESIZE的值清空

MAXPIECESIZE设置为无限大，自然可以解决备份集超过上限的问题，也可以不用配置%p，但是不推荐使用这种方法，如果因为数据库的数据量非常大，将导致生成的备份集过大，不利于存储和恢复

RMAN> CONFIGURE CHANNEL DEVICE TYPE DISK clear;

old RMAN configuration parameters:

CONFIGURE CHANNEL DEVICE TYPE DISK MAXPIECESIZE 100 M;

old RMAN configuration parameters are successfully deleted --原来配置的MAXPIECESIZE的值清空完成

RMAN> show all;

RMAN configuration parameters are:

CONFIGURE RETENTION POLICY TO REDUNDANCY 5;

CONFIGURE BACKUP OPTIMIZATION ON;

CONFIGURE DEFAULT DEVICE TYPE TO DISK;

CONFIGURE CONTROLFILE AUTOBACKUP ON;

CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO ‘/u01/orabackup/backupsets/ora10g-%F.ctl‘;

CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET;

CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default

CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default

CONFIGURE MAXSETSIZE TO UNLIMITED; # default

CONFIGURE ENCRYPTION FOR DATABASE OFF; # default

CONFIGURE ENCRYPTION ALGORITHM ‘AES128‘; # default

CONFIGURE ARCHIVELOG DELETION POLICY TO NONE;

CONFIGURE SNAPSHOT CONTROLFILE NAME TO ‘/u01/app/oracle/product/10.2.0/db_1/dbs/snapcf_ora10g.f‘; # default

可以看到，刚才MAXPIECESIZE的值在show all中已经不存在了，也就是对备份片没有限制了

再次进行备份，可以通过脚本运行，也可以单独执行下面的备份语句：

RMAN> backup as compressed backupset database format ‘$RMAN_BACKUPSETS/$ORACLE_SID-%I_%T_%t_%s.db‘ tag ‘db_bak‘ plus archivelog
format ‘$RMAN_BACKUPSETS/$ORACLE_SID-%I_%T_%t_%s.arc‘ not backed up 1 times delete all input tag ‘arc_bak‘;

[[email protected] backupsets]$ . ../scripts/backup_full.sh

RMAN> RMAN> RMAN> RMAN> RMAN> RMAN> RMAN> RMAN> RMAN> RMAN> 2> 3> RMAN> RMAN> RMAN> RMAN>

[[email protected] backupsets]$ ls -lrth ../backupsets/

total 553M