[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。

-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

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。

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：

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：

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：

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：

    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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posted @ 2021-04-10 11:17 健哥的数据花园阅读(998) 评论(0) 收藏举报

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[Oracle工程师手记] 提高 RMAN 备份性能的技巧之 Section Size

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