[Oracle工程师手记] 提高 RMAN 备份性能的技巧之 Section Size
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在某些情况下,section size 的使用,在 RMAN 备份中,会大幅度地提高备份速度。这是因为,如果不使用 section size ,那么无论我在备份时设置了多少个channel,在任何一个时刻,对每一个文件而言,只能有一个channel 连接到这个文件上执行读取和备份。
例如,下面的试验中,我开了 8 个 channel 进行备份。
1 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 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 | -bash-4.1$ rman target / Recovery Manager: Release 12.2.0.1.0 - Production on Sat Apr 10 09:35:01 2021 Copyright (c) 1982, 2017, Oracle and / or its affiliates. All rights reserved. connected to target database : ORCL1220 (DBID=1362151495) RMAN> run{ ALLOCATE CHANNEL CH1 TYPE DISK; ALLOCATE CHANNEL CH2 TYPE DISK; ALLOCATE CHANNEL CH3 TYPE DISK; ALLOCATE CHANNEL CH4 TYPE DISK; ALLOCATE CHANNEL CH5 TYPE DISK; ALLOCATE CHANNEL CH6 TYPE DISK; ALLOCATE CHANNEL CH7 TYPE DISK; ALLOCATE CHANNEL CH8 TYPE DISK; backup database ; } using target database control file instead of recovery catalog allocated channel: CH1 channel CH1: SID=66 device type=DISK allocated channel: CH2 channel CH2: SID=59 device type=DISK allocated channel: CH3 channel CH3: SID=57 device type=DISK allocated channel: CH4 channel CH4: SID=61 device type=DISK allocated channel: CH5 channel CH5: SID=62 device type=DISK allocated channel: CH6 channel CH6: SID=69 device type=DISK allocated channel: CH7 channel CH7: SID=70 device type=DISK allocated channel: CH8 channel CH8: SID=63 device type=DISK Starting backup at 20210410_09:35:31 channel CH1: starting full datafile backup set channel CH1: specifying datafile(s) in backup set input datafile file number=00001 name =/refresh/home/app/12.2.0.1/oracle/oradata/orcl12201/system01.dbf channel CH1: starting piece 1 at 20210410_09:35:32 channel CH2: starting full datafile backup set channel CH2: specifying datafile(s) in backup set input datafile file number=00003 name =/refresh/home/app/12.2.0.1/oracle/oradata/orcl12201/sysaux01.dbf channel CH2: starting piece 1 at 20210410_09:35:32 *** channel CH3: starting full datafile backup set channel CH3: specifying datafile(s) in backup set input datafile file number=00005 name =/refresh/home/datafile/df001.dbf channel CH3: starting piece 1 at 20210410_09:35:32 channel CH4: starting full datafile backup set channel CH4: specifying datafile(s) in backup set input datafile file number=00004 name =/refresh/home/app/12.2.0.1/oracle/oradata/orcl12201/undotbs01.dbf channel CH4: starting piece 1 at 20210410_09:35:32 channel CH5: starting full datafile backup set channel CH5: specifying datafile(s) in backup set input datafile file number=00007 name =/refresh/home/app/12.2.0.1/oracle/oradata/orcl12201/users01.dbf channel CH5: starting piece 1 at 20210410_09:35:32 channel CH3: finished piece 1 at 20210410_09:35:39 piece handle=/refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0ivrubf4_1_1 tag=TAG20210410T093531 comment=NONE channel CH3: backup set complete, elapsed time : 00:00:07 channel CH5: finished piece 1 at 20210410_09:35:39 piece handle=/refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0kvrubf4_1_1 tag=TAG20210410T093531 comment=NONE channel CH5: backup set complete, elapsed time : 00:00:07 channel CH4: finished piece 1 at 20210410_09:35:47 piece handle=/refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0jvrubf4_1_1 tag=TAG20210410T093531 comment=NONE channel CH4: backup set complete, elapsed time : 00:00:15<br> channel CH1: finished piece 1 at 20210410_09:36:07 piece handle=/refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0gvrubf4_1_1 tag=TAG20210410T093531 comment=NONE channel CH1: backup set complete, elapsed time : 00:00:35 *** channel CH2: finished piece 1 at 20210410_09:36:07 piece handle=/refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0hvrubf4_1_1 tag=TAG20210410T093531 comment=NONE channel CH2: backup set complete, elapsed time : 00:00:35 Finished backup at 20210410_09:36:07 *** Starting Control File and SPFILE Autobackup at 20210410_09:36:07 piece handle=/refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/c-1362151495-20210410-01 comment=NONE Finished Control File and SPFILE Autobackup at 20210410_09:36:09 released channel: CH1 released channel: CH2 released channel: CH3 released channel: CH4 released channel: CH5 released channel: CH6 released channel: CH7 released channel: CH8 RMAN> |
我的数据文件只有 5 个,所以 CH6、CH7、CH8 并没有被使用。我的 CH2 对 sysaux01.dbf 进行备份,它从 9:35:32 开始,到 9:36:07 结束。 而我的 CH4 比它早结束,它在 9:35:47 就结束了对 undotbs01.dbf 的备份,CH4 完成对 undotbs01.dbf 已经空闲,它并没有过来帮助CH2 来备份 sysaux01.dbf 。
所以,在不指定 section size 的情况下,一个文件只能被一个 Channel 访问。如果客户的环境中有一些文件十分的巨大,那么只有一个 channel 对其处理(只有一个CPU参与备份),那么效率就会是相当低下的。
所以,我们需要使用 section size。举例来说, 将 section size 设置为 200M。
1 2 3 4 5 6 7 8 9 10 11 | run{ ALLOCATE CHANNEL CH1 TYPE DISK; ALLOCATE CHANNEL CH2 TYPE DISK; ALLOCATE CHANNEL CH3 TYPE DISK; ALLOCATE CHANNEL CH4 TYPE DISK; ALLOCATE CHANNEL CH5 TYPE DISK; ALLOCATE CHANNEL CH6 TYPE DISK; ALLOCATE CHANNEL CH7 TYPE DISK; ALLOCATE CHANNEL CH8 TYPE DISK; backup database section size 200M; } |
这时,备份的过程是这样的:
1 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 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 | released channel: ORA_DISK_1 allocated channel: CH1 channel CH1: SID=66 device type=DISK allocated channel: CH2 channel CH2: SID=59 device type=DISK allocated channel: CH3 channel CH3: SID=57 device type=DISK allocated channel: CH4 channel CH4: SID=61 device type=DISK allocated channel: CH5 channel CH5: SID=62 device type=DISK allocated channel: CH6 channel CH6: SID=69 device type=DISK allocated channel: CH7 channel CH7: SID=70 device type=DISK allocated channel: CH8 channel CH8: SID=63 device type=DISK Starting backup at 20210410_09:52:44 channel CH1: starting full datafile backup set channel CH1: specifying datafile(s) in backup set input datafile file number=00001 name =/refresh/home/app/12.2.0.1/oracle/oradata/orcl12201/system01.dbf backing up blocks 1 through 25600 channel CH1: starting piece 1 at 20210410_09:52:44 channel CH2: starting full datafile backup set channel CH2: specifying datafile(s) in backup set input datafile file number=00003 name =/refresh/home/app/12.2.0.1/oracle/oradata/orcl12201/sysaux01.dbf backing up blocks 1 through 25600 channel CH2: starting piece 1 at 20210410_09:52:44 channel CH3: starting full datafile backup set channel CH3: specifying datafile(s) in backup set input datafile file number=00005 name =/refresh/home/datafile/df001.dbf channel CH3: starting piece 1 at 20210410_09:52:44 channel CH4: starting full datafile backup set channel CH4: specifying datafile(s) in backup set input datafile file number=00004 name =/refresh/home/app/12.2.0.1/oracle/oradata/orcl12201/undotbs01.dbf channel CH4: starting piece 1 at 20210410_09:52:45 channel CH5: starting full datafile backup set channel CH5: specifying datafile(s) in backup set input datafile file number=00007 name =/refresh/home/app/12.2.0.1/oracle/oradata/orcl12201/users01.dbf channel CH5: starting piece 1 at 20210410_09:52:45 channel CH6: starting full datafile backup set channel CH6: specifying datafile(s) in backup set input datafile file number=00001 name =/refresh/home/app/12.2.0.1/oracle/oradata/orcl12201/system01.dbf backing up blocks 25601 through 51200 channel CH6: starting piece 2 at 20210410_09:52:47 channel CH7: starting full datafile backup set channel CH7: specifying datafile(s) in backup set input datafile file number=00001 name =/refresh/home/app/12.2.0.1/oracle/oradata/orcl12201/system01.dbf backing up blocks 51201 through 76800 channel CH7: starting piece 3 at 20210410_09:52:47 channel CH8: starting full datafile backup set channel CH8: specifying datafile(s) in backup set input datafile file number=00001 name =/refresh/home/app/12.2.0.1/oracle/oradata/orcl12201/system01.dbf backing up blocks 76801 through 102400 channel CH8: starting piece 4 at 20210410_09:52:47 channel CH1: finished piece 1 at 20210410_09:52:47 piece handle=/refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0mvrucfc_1_1 tag=TAG20210410T095244 comment=NONE channel CH1: backup set complete, elapsed time : 00:00:03 channel CH1: starting full datafile backup set channel CH1: specifying datafile(s) in backup set input datafile file number=00001 name =/refresh/home/app/12.2.0.1/oracle/oradata/orcl12201/system01.dbf backing up blocks 102401 through 106240 channel CH1: starting piece 5 at 20210410_09:52:48 channel CH2: finished piece 1 at 20210410_09:52:48 piece handle=/refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0nvrucfc_1_1 tag=TAG20210410T095244 comment=NONE channel CH2: backup set complete, elapsed time : 00:00:04 channel CH2: starting full datafile backup set channel CH2: specifying datafile(s) in backup set input datafile file number=00003 name =/refresh/home/app/12.2.0.1/oracle/oradata/orcl12201/sysaux01.dbf backing up blocks 25601 through 51200 channel CH2: starting piece 2 at 20210410_09:52:49 channel CH3: finished piece 1 at 20210410_09:52:49 piece handle=/refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0ovrucfc_1_1 tag=TAG20210410T095244 comment=NONE channel CH3: backup set complete, elapsed time : 00:00:05 channel CH3: starting full datafile backup set channel CH3: specifying datafile(s) in backup set input datafile file number=00003 name =/refresh/home/app/12.2.0.1/oracle/oradata/orcl12201/sysaux01.dbf backing up blocks 51201 through 76800 channel CH3: starting piece 3 at 20210410_09:52:51 channel CH4: finished piece 1 at 20210410_09:52:51 piece handle=/refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0pvrucfd_1_1 tag=TAG20210410T095244 comment=NONE channel CH4: backup set complete, elapsed time : 00:00:06 channel CH4: starting full datafile backup set channel CH4: specifying datafile(s) in backup set input datafile file number=00003 name =/refresh/home/app/12.2.0.1/oracle/oradata/orcl12201/sysaux01.dbf backing up blocks 76801 through 93440 channel CH4: starting piece 4 at 20210410_09:52:52 channel CH5: finished piece 1 at 20210410_09:52:52 piece handle=/refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0qvrucfd_1_1 tag=TAG20210410T095244 comment=NONE channel CH5: backup set complete, elapsed time : 00:00:07 channel CH1: finished piece 5 at 20210410_09:52:52 piece handle=/refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0mvrucfc_5_1 tag=TAG20210410T095244 comment=NONE channel CH1: backup set complete, elapsed time : 00:00:04 channel CH6: finished piece 2 at 20210410_09:52:53 piece handle=/refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0mvrucfc_2_1 tag=TAG20210410T095244 comment=NONE channel CH6: backup set complete, elapsed time : 00:00:06 channel CH7: finished piece 3 at 20210410_09:52:53 piece handle=/refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0mvrucfc_3_1 tag=TAG20210410T095244 comment=NONE channel CH7: backup set complete, elapsed time : 00:00:06 channel CH8: finished piece 4 at 20210410_09:52:53 piece handle=/refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0mvrucfc_4_1 tag=TAG20210410T095244 comment=NONE channel CH8: backup set complete, elapsed time : 00:00:06 channel CH2: finished piece 2 at 20210410_09:53:00 piece handle=/refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0nvrucfc_2_1 tag=TAG20210410T095244 comment=NONE channel CH2: backup set complete, elapsed time : 00:00:11 channel CH3: finished piece 3 at 20210410_09:53:00 piece handle=/refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0nvrucfc_3_1 tag=TAG20210410T095244 comment=NONE channel CH3: backup set complete, elapsed time : 00:00:09 channel CH4: finished piece 4 at 20210410_09:53:00 piece handle=/refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0nvrucfc_4_1 tag=TAG20210410T095244 comment=NONE channel CH4: backup set complete, elapsed time : 00:00:08 Finished backup at 20210410_09:53:00 Starting Control File and SPFILE Autobackup at 20210410_09:53:00 piece handle=/refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/c-1362151495-20210410-02 comment=NONE Finished Control File and SPFILE Autobackup at 20210410_09:53:01 released channel: CH1 released channel: CH2 released channel: CH3 released channel: CH4 released channel: CH5 released channel: CH6 released channel: CH7 released channel: CH8 RMAN> |
可以看到,这次,CH1、CH2 一直到 CH8,都参与了备份过程。 为了看清它的过程,可以把 CH1 关联部分摘要出来:
1 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 36 37 38 39 40 41 | allocated channel: CH1 channel CH1: SID=66 device type=DISK ...... Starting backup at 20210410_09:52:44 channel CH1: starting full datafile backup set channel CH1: specifying datafile(s) in backup set input datafile file number=00001 name =/refresh/home/app/12.2.0.1/oracle/oradata/orcl12201/system01.dbf backing up blocks 1 through 25600 channel CH1: starting piece 1 at 20210410_09:52:44 ...... channel CH1: finished piece 1 at 20210410_09:52:47 piece handle=/refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0mvrucfc_1_1 tag=TAG20210410T095244 comment=NONE channel CH1: backup set complete, elapsed time : 00:00:03 ...... channel CH1: starting full datafile backup set channel CH1: specifying datafile(s) in backup set input datafile file number=00001 name =/refresh/home/app/12.2.0.1/oracle/oradata/orcl12201/system01.dbf backing up blocks 102401 through 106240 channel CH1: starting piece 5 at 20210410_09:52:48 ...... channel CH1: finished piece 5 at 20210410_09:52:52 piece handle=/refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0mvrucfc_5_1 tag=TAG20210410T095244 comment=NONE channel CH1: backup set complete, elapsed time : 00:00:04 ...... released channel: CH1 released channel: CH2 released channel: CH3 released channel: CH4 released channel: CH5 released channel: CH6 released channel: CH7 released channel: CH8 RMAN> |
可以看到,从 9:52:47 ,CH1 完成了第一次的备份之后,又马不停蹄地开始了第二次的备份,9:52:48 CH1 再次开始备份,直到 9:52:52 结束。,使用了 section size ,就可以把一个文件理解成许多个小文件,各个channel 会不断地读取这些个小文件,直到所有的小文件都被读取过。
而备份后结果是这样的:
1 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 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 | RMAN> list backup; List of Backup Sets =================== BS Key Type LV Size Device Type Elapsed Time Completion Time ------- ---- -- ---------- ----------- ------------ ----------------- 20 Full 8.42M DISK 00:00:00 20210410_09:52:45 BP Key : 20 Status: AVAILABLE Compressed: NO Tag: TAG20210410T095244 Piece Name : /refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0pvrucfd_1_1 List of Datafiles in backup set 20 File LV Type Ckp SCN Ckp Time Abs Fuz SCN Sparse Name ---- -- ---- ---------- ----------------- ----------- ------ ---- 4 Full 1944008 20210410_09:52:45 NO /refresh/home/app/12.2.0.1/oracle/oradata/orcl12201/undotbs01.dbf BS Key Type LV Size Device Type Elapsed Time Completion Time ------- ---- -- ---------- ----------- ------------ ----------------- 21 Full 26.44M DISK 00:00:00 20210410_09:52:45 BP Key : 21 Status: AVAILABLE Compressed: NO Tag: TAG20210410T095244 Piece Name : /refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0qvrucfd_1_1 List of Datafiles in backup set 21 File LV Type Ckp SCN Ckp Time Abs Fuz SCN Sparse Name ---- -- ---- ---------- ----------------- ----------- ------ ---- 7 Full 1944009 20210410_09:52:45 NO /refresh/home/app/12.2.0.1/oracle/oradata/orcl12201/users01.dbf BS Key Type LV Size Device Type Elapsed Time Completion Time ------- ---- -- ---------- ----------- ------------ ----------------- 22 Full 23.92M DISK 00:00:01 20210410_09:52:45 BP Key : 22 Status: AVAILABLE Compressed: NO Tag: TAG20210410T095244 Piece Name : /refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0ovrucfc_1_1 List of Datafiles in backup set 22 File LV Type Ckp SCN Ckp Time Abs Fuz SCN Sparse Name ---- -- ---- ---------- ----------------- ----------- ------ ---- 5 Full 1944007 20210410_09:52:45 NO /refresh/home/datafile/df001.dbf BS Key Type LV Size Device Type Elapsed Time Completion Time ------- ---- -- ---------- ----------- ------------ ----------------- 23 Full 695.90M DISK 00:00:04 20210410_09:52:48 List of Datafiles in backup set 23 File LV Type Ckp SCN Ckp Time Abs Fuz SCN Sparse Name ---- -- ---- ---------- ----------------- ----------- ------ ---- 1 Full 1944005 20210410_09:52:44 NO /refresh/home/app/12.2.0.1/oracle/oradata/orcl12201/system01.dbf Backup Set Copy #1 of backup set 23 Device Type Elapsed Time Completion Time Compressed Tag ----------- ------------ ----------------- ---------- --- DISK 00:00:04 20210410_09:52:48 NO TAG20210410T095244 List of Backup Pieces for backup set 23 Copy #1 BP Key Pc# Status Piece Name ------- --- ----------- ---------- 23 1 AVAILABLE /refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0mvrucfc_1_1 26 2 AVAILABLE /refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0mvrucfc_2_1 28 3 AVAILABLE /refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0mvrucfc_3_1 27 4 AVAILABLE /refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0mvrucfc_4_1 25 5 AVAILABLE /refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0mvrucfc_5_1 BS Key Type LV Size Device Type Elapsed Time Completion Time ------- ---- -- ---------- ----------- ------------ ----------------- 24 Full 570.30M DISK 00:00:09 20210410_09:52:53 List of Datafiles in backup set 24 File LV Type Ckp SCN Ckp Time Abs Fuz SCN Sparse Name ---- -- ---- ---------- ----------------- ----------- ------ ---- 3 Full 1944006 20210410_09:52:44 NO /refresh/home/app/12.2.0.1/oracle/oradata/orcl12201/sysaux01.dbf Backup Set Copy #1 of backup set 24 Device Type Elapsed Time Completion Time Compressed Tag ----------- ------------ ----------------- ---------- --- DISK 00:00:09 20210410_09:52:57 NO TAG20210410T095244 List of Backup Pieces for backup set 24 Copy #1 BP Key Pc# Status Piece Name ------- --- ----------- ---------- 24 1 AVAILABLE /refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0nvrucfc_1_1 31 2 AVAILABLE /refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0nvrucfc_2_1 30 3 AVAILABLE /refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0nvrucfc_3_1 29 4 AVAILABLE /refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0nvrucfc_4_1 BS Key Type LV Size Device Type Elapsed Time Completion Time ------- ---- -- ---------- ----------- ------------ ----------------- 25 Full 10.19M DISK 00:00:00 20210410_09:53:00 BP Key : 32 Status: AVAILABLE Compressed: NO Tag: TAG20210410T095300 Piece Name : /refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/c-1362151495-20210410-02 SPFILE Included: Modification time : 20210410_09:33:06 SPFILE db_unique_name: ORCL12201 Control File Included: Ckp SCN: 1944061 Ckp time : 20210410_09:53:00 RMAN> |
可以看到,对一些个数据文件,产生了多个备份文件。比如,对 system01.dbf 的备份产生的备份集 23,它包含的备份片(文件)有下面这些:
1 2 3 4 5 6 7 8 | List of Backup Pieces for backup set 23 Copy #1 BP Key Pc# Status Piece Name ------- --- ----------- ---------- 23 1 AVAILABLE /refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0mvrucfc_1_1 26 2 AVAILABLE /refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0mvrucfc_2_1 28 3 AVAILABLE /refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0mvrucfc_3_1 27 4 AVAILABLE /refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0mvrucfc_4_1 25 5 AVAILABLE /refresh/home/app/12.2.0.1/oracle/product/12.2.0.1/dbhome3/dbs/0mvrucfc_5_1 |
一般而言,和产生的备份文件数量比起来,因为备份速度有可能大幅度提高,使用 section size 很多时候是可以接受的。我这里给出的仅仅是一个例子,整体备份的时间本来就很短。如果真正的生产环境中,数据文件很大时,section size 就值得考虑了。
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