ORACLE RMAN 高级话题一(分片与压缩)

关于maxsize 和 section size

我想在备份的时候限制文件的大小，如下：

RMAN> backup tablespace users maxsetsize 1024m; Starting backup at 11-AUG-17 using channel ORA_DISK_1 using channel ORA_DISK_2 using channel ORA_DISK_3 using channel ORA_DISK_4 using channel ORA_DISK_5 using channel ORA_DISK_6 RMAN-00571: =========================================================== RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS =============== RMAN-00571: =========================================================== RMAN-03002: failure of backup command at 08/11/2017 10:21:38 RMAN-06183: datafile or datafile copy /u01/app/oracle/oradata/orcl/users01.dbf (file number 4) larger than MAXSETSIZE

在这里我备份的文件大小超过maxsize，所以报错了。

RMAN> backup section size 500m tablespace users; Starting backup at 11-AUG-17 using channel ORA_DISK_1 using channel ORA_DISK_2 using channel ORA_DISK_3 using channel ORA_DISK_4 using channel ORA_DISK_5 using channel ORA_DISK_6 channel ORA_DISK_1: starting full datafile backup set channel ORA_DISK_1: specifying datafile(s) in backup set input datafile file number=00004 name=/u01/app/oracle/oradata/orcl/users01.dbf backing up blocks 1 through 64000 channel ORA_DISK_1: starting piece 1 at 11-AUG-17 channel ORA_DISK_2: starting full datafile backup set channel ORA_DISK_2: specifying datafile(s) in backup set input datafile file number=00004 ×××× ×××××（中间有省略） name=/u01/app/oracle/oradata/orcl/users01.dbf backing up blocks 320001 through 384000 channel ORA_DISK_6: starting piece 6 at 11-AUG-17 channel ORA_DISK_1: finished piece 1 at 11-AUG-17 piece handle=/u02/backup/ORCL/backupset/2017_08_11/o1_mf_nnndf_TAG20170811T102414_drt5bgz1_.bkp tag=TAG20170811T102414 comment=NONE channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01 channel ORA_DISK_1: starting full datafile backup set channel ORA_DISK_1: specifying datafile(s) in backup set input datafile file number=00004 name=/u01/app/oracle/oradata/orcl/users01.dbf backing up blocks 384001 through 398240 channel ORA_DISK_1: starting piece 7 at 11-AUG-17 channel ORA_DISK_2: finished piece 2 at 11-AUG-17 piece handle=/u02/backup/ORCL/backupset/2017_08_11/o1_mf_nnndf_TAG20170811T102414_drt5bhfy_.bkp tag=TAG20170811T102414 comment=NONE channel ORA_DISK_2: backup set complete, elapsed time: 00:00:00 channel ORA_DISK_3: finished piece 3 at 11-AUG-17 piece handle=/u02/backup/ORCL/backupset/2017_08_11/o1_mf_nnndf_TAG20170811T102414_drt5bhhh_.bkp tag=TAG20170811T102414 comment=NONE channel ORA_DISK_3: backup set complete, elapsed time: 00:00:00 channel ORA_DISK_4: finished piece 4 at 11-AUG-17 piece handle=/u02/backup/ORCL/backupset/2017_08_11/o1_mf_nnndf_TAG20170811T102414_drt5bhjr_.bkp tag=TAG20170811T102414 comment=NONE ×××　×××　（中间有省略） handle=/u02/backup/ORCL/backupset/2017_08_11/o1_mf_nnndf_TAG20170811T102414_drt5bhmm_.bkp tag=TAG20170811T102414 comment=NONE channel ORA_DISK_6: backup set complete, elapsed time: 00:00:00 Finished backup at 11-AUG-17 Starting Control File and SPFILE Autobackup at 11-AUG-17 piece handle=/u02/backup/ORCL/autobackup/2017_08_11/o1_mf_s_951733455_drt5bhyq_.bkp comment=NONE Finished Control File and SPFILE Autobackup at 11-AUG-17 RMAN> 我想这样达成了限制文件大小的目地 [oracle@hdp 2017_08_11]$ ll -h total 43M -rw-r-----. 1 oracle oinstall 38M Aug 11 10:24 o1_mf_nnndf_TAG20170811T102414_drt5bgz1_.bkp -rw-r-----. 1 oracle oinstall 5.1M Aug 11 10:24 o1_mf_nnndf_TAG20170811T102414_drt5bhfy_.bkp -rw-r-----. 1 oracle oinstall 40K Aug 11 10:24 o1_mf_nnndf_TAG20170811T102414_drt5bhhh_.bkp -rw-r-----. 1 oracle oinstall 40K Aug 11 10:24 o1_mf_nnndf_TAG20170811T102414_drt5bhjr_.bkp -rw-r-----. 1 oracle oinstall 40K Aug 11 10:24 o1_mf_nnndf_TAG20170811T102414_drt5bhl8_.bkp -rw-r-----. 1 oracle oinstall 40K Aug 11 10:24 o1_mf_nnndf_TAG20170811T102414_drt5bhmm_.bkp -rw-r-----. 1 oracle oinstall 56K Aug 11 10:24 o1_mf_nnndf_TAG20170811T102414_drt5bhqg_.bkp -rw-r--r--. 1 oracle oinstall 369 Aug 11 08:28 rman.sh

rman 的默认压缩方式：

CONFIGURE COMPRESSION ALGORITHM ‘BASIC’ AS OF RELEASE ‘DEFAULT’ OPTIMIZE FOR LOAD TRUE ; # default

我们用默认压缩算法：

RMAN> backup as compressed backupset database ; drwxr-x---. 2 oracle oinstall 4096 Aug 11 11:01 2017_08_11 [oracle@hdp backupset]$ du -sh * 285M 2017_08_11

这里修改默认的压缩算法

RMAN> CONFIGURE COMPRESSION ALGORITHM 'medium' AS OF RELEASE 'DEFAULT' 2> ; using target database control file instead of recovery catalog new RMAN configuration parameters: CONFIGURE COMPRESSION ALGORITHM 'medium' AS OF RELEASE 'DEFAULT' OPTIMIZE FOR LOAD TRUE; new RMAN configuration parameters are successfully stored RMAN>

再次更改为最高等级的算法

RMAN> CONFIGURE COMPRESSION ALGORITHM 'HIGH' AS OF RELEASE 'DEFAULT' OPTIMIZE FOR LOAD TRUE;

测试了一下三种压缩算法的结果：

[oracle@hdp backupset]$ du -sh * 278M 2017_08_11.basic 229M 2017_08_11.high 308M 2017_08_11.medium

结果是high级别压缩时最狠的，其次是基本压缩，当然压缩比率越大，越耗CPU。所以不要在系统繁忙阶段进行备份。

监控一下cpu的运行状况 [oracle@hdp backupset]$ mpstat 2 Linux 2.6.32-358.el6.x86_64 (hdp.oracle.com) 08/11/2017 _x86_64_ (4 CPU) 11:25:35 AM CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle 11:25:37 AM all 49.50 0.00 0.38 0.00 0.00 0.00 0.00 0.00 50.13 11:25:39 AM all 49.87 0.00 0.89 0.00 0.00 0.89 0.00 0.00 48.35 11:25:41 AM all 49.31 0.00 0.50 0.00 0.00 0.00 0.00 0.00 50.19 11:25:43 AM all 49.68 0.00 0.13 0.00 0.00 0.13 0.00 0.00 50.06 11:25:45 AM all 49.87 0.00 0.25 0.00 0.00 0.00 0.00 0.00 49.87