Data Guard的搭建可以使用GC圖形化安裝，優缺點很明顯，優點就是圖形化操作，符合國人的習慣(據secooler介紹外國程式設計師能用圖形化做的事就一定用圖形做，因為boss看得懂，和國人正相反。。。)，缺點就是如同Windows一樣，宛如黑盒，換句話說，要時刻祈禱不要出問題，否則有時很難知道他為什麼掛了。。。

Data Guard還可以使用命令列操作，正如各位所知，圖形化的任何操作背後，其實都是使用的命令。OCM第七場景考試中，我也是糾結了許久，臨開始前才決定使用手工方式建立DG，怕的就是圖形安裝的不確定性。

當然，作為練習，兩種方式都熟悉下沒什麼不好。最近新找了兩臺機器資源，於是決定搭建一下DG的測試環境，以備後用。

環境準備：
OS：RH Linux
配置：2C4G，40G磁碟空間
資料庫：11.2.0.4
主庫SID：BEIJING，單例項
備庫SID：GUOAN，單例項

1.主庫準備工作

編輯listener.ora，配置主庫靜態監聽：

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (GLOBAL_DBNAME = BEIJING)
      (ORACLE_HOME = /u01/app/oracle/product/11.2.0.4)
      (SID_NAME = BEIJING)
    )
  )

LISTENER
 
 =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = bill02)(PORT = 1521))
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
    )
  )

ADR_BASE_LISTENER = /u01/app/oracle

編輯tnsnames.ora，配置備庫連線串：

GUOAN =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = bill01)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = GUOAN)
    )
  )
 

設定force_logging引數：

SYS@BEIJING> alter database force logging;

檢視是否開啟歸檔：

[email protected]> archive log list;
Database log mode              Archive Mode
Automatic archival             Enabled
Archive destination            USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence     6
Next log sequence to archive   8
Current log sequence           8

若未開啟，將庫置於mount狀態，執行：

alter database archivelog;

確認shared_servers、max_shared_servers、dispatchers和max_dispatchers引數是否置空。(此步驟為了防止建立過程出錯，實際驗證不設定亦可)。

檢視主庫日誌組：

SYS@BEIJING> select group#, member from v$logfile;
    GROUP# MEMBER
---------- --------------------------------------------------
         1 /u01/app/oracle/oradata/BEIJING/redo01.log
         2 /u01/app/oracle/oradata/BEIJING/redo02.log
         3 /u01/app/oracle/oradata/BEIJING/redo03.log

一共有三組，再增加四組standby日誌：

SYS@BEIJING> alter database add standby logfile '/u01/app/oracle/oradata/BEIJING/redo04.log' size 100M;
SYS@BEIJING> alter database add standby logfile '/u01/app/oracle/oradata/BEIJING/redo05.log' size 100M;
SYS@BEIJING> alter database add standby logfile '/u01/app/oracle/oradata/BEIJING/redo06.log' size 100M;
SYS@BEIJING> alter database add standby logfile '/u01/app/oracle/oradata/BEIJING/redo07.log' size 100M;

SYS@BEIJING> select group#, member, type from v$logfile;
GROUP# MEMBER                                        TYPE
---------- ---------------------------------------- -------
1 /u01/app/oracle/oradata/BEIJING/redo01.log         ONLINE
2 /u01/app/oracle/oradata/BEIJING/redo02.log         ONLINE
3 /u01/app/oracle/oradata/BEIJING/redo03.log         ONLINE
4 /u01/app/oracle/oradata/BEIJING/redo04.log         STANDBY
5 /u01/app/oracle/oradata/BEIJING/redo05.log         STANDBY
6 /u01/app/oracle/oradata/BEIJING/redo06.log         STANDBY
7 /u01/app/oracle/oradata/BEIJING/redo07.log         STANDBY

編輯pfile檔案，

DB_NAME=BEIJING
DB_UNIQUE_NAME=BEIJING
LOG_ARCHIVE_CONFIG='DG_CONFIG=(BEIJING,GUOAN)’  －－順序填寫主備庫
LOG_ARCHIVE_DEST_1=
 'LOCATION=/home/oracle/flash                   －－location表示本機
  VALID_FOR=(ALL_LOGFILES,ALL_ROLES)            －－填寫主庫歸檔路徑
  DB_UNIQUE_NAME=BEIJING'
LOG_ARCHIVE_DEST_2=
 'SERVICE=GUOAN ASYNC                           －－service表示另一臺機器
  VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE)
  DB_UNIQUE_NAME=GUOAN’                         －－填寫備庫DB名稱
LOG_ARCHIVE_DEST_STATE_1=ENABLE
LOG_ARCHIVE_DEST_STATE_2=ENABLE
REMOTE_LOGIN_PASSWORDFILE=EXCLUSIVE
LOG_ARCHIVE_FORMAT=%t_%s_%r.arc
LOG_ARCHIVE_MAX_PROCESSES=4        －－最大歸檔程序數官方文件預設30，此處改為4

FAL_SERVER=GUOAN        －－為了切換後主備角色互換使用，Fetch Archived Log縮寫
DB_FILE_NAME_CONVERT='GUOAN',’BEIJING’          －－資料檔案目錄結構對應關係
LOG_FILE_NAME_CONVERT='GUOAN',’BEIJING’         －－日誌檔案目錄結構對應關係
STANDBY_FILE_MANAGEMENT=AUTO    －－主庫資料檔案修改，備庫可以選擇自動或手工管理

將主庫已經改好的引數檔案和密碼檔案傳至備庫dbs路徑下：

[oracle@bill02 dbs]$ scp initBEIJING.ora oracle@bill01:/u01/app/oracle/product/11.2.0.4/dbs/initGUOAN.ora
[oracle@bill02 dbs]$ scp orapwBEIJING oracle@bill01:/u01/app/oracle/product/11.2.0.4/dbs/orapwGUOAN

建立主庫spfile，並啟動：

SYS@BEIJING> create spfile from pfile;
SYS@BEIJING> startup;

2.備庫準備工作

編輯tnsnames.ora檔案，建立主庫連線串：

BEIJING =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = bill02)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = BEIJING)
    )
  )

建立備庫監聽：略

編輯備庫pfile檔案，

db_name=‘BEIJING’                   －－注意此處，主備庫的db_name引數要一致
memory_target=1G
processes = 150
audit_file_dest='/u01/app/oracle/admin/guoan/adump'
audit_trail ='db'
db_block_size=8192
db_domain=''
db_recovery_file_dest='/u01/app/oracle/fast_recovery_area'
db_recovery_file_dest_size=2G
diagnostic_dest='/u01/app/oracle'
dispatchers='(PROTOCOL=TCP) (SERVICE=GUOANXDB)'
open_cursors=300
remote_login_passwordfile='EXCLUSIVE'
undo_tablespace='UNDOTBS'
control_files = (/u01/app/oracle/oradata/GUOAN/control01.ctl, /u01/app/oracle/oradata/GUOAN/control02.ctl)
compatible ='11.2.0'

DB_UNIQUE_NAME=GUOAN
LOG_ARCHIVE_CONFIG='DG_CONFIG=(GUOAN,BEIJING)'
LOG_ARCHIVE_DEST_1=
 'LOCATION=/home/oracle/flash
  VALID_FOR=(ALL_LOGFILES,ALL_ROLES)
  DB_UNIQUE_NAME=GUOAN'
LOG_ARCHIVE_DEST_2=
 'SERVICE=BEIJING ASYNC
  VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE)
  DB_UNIQUE_NAME=BEIJING'
LOG_ARCHIVE_DEST_STATE_1=ENABLE
LOG_ARCHIVE_DEST_STATE_2=ENABLE
REMOTE_LOGIN_PASSWORDFILE=EXCLUSIVE
LOG_ARCHIVE_FORMAT=%t_%s_%r.arc
LOG_ARCHIVE_MAX_PROCESSES=4

FAL_SERVER=BEIJING
DB_FILE_NAME_CONVERT='BEIJING','GUOAN'
LOG_FILE_NAME_CONVERT='BEIJING','GUOAN'
STANDBY_FILE_MANAGEMENT=AUTO

可以採用替換的方式來修改備庫pfile檔案：
(1) 將BEIJING替換為中間變數TMP_BEIJING；
(2) 將GUOAN替換為BEIJING；
(3) 將TMP_BEIJING替換為GUOAN；

建立spfile，啟動備庫：

SYS@GUOAN> create spfile from pfile;

SYS@GUOAN> startup
ORACLE instance started.
Total System Global Area 1068937216 bytes
Fixed Size                  2260088 bytes
Variable Size             671089544 bytes
Database Buffers          390070272 bytes
Redo Buffers                5517312 bytes
ORA-00205: error in identifying control file, check alert log for more info

此處有報錯，可以暫時忽略，因為備庫還未有控制檔案。

3.主備庫檔案傳輸

此處我們採用RMAN來將主庫檔案傳至備庫：

[email protected] dbs]$ rman target / auxiliary sys/[email protected]

Recovery Manager: Release 11.2.0.4.0 - Production on Fri Jul 29 09:46:22 2016
Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.
connected to target database: BEIJING (DBID=882855131)
connected to auxiliary database: BEIJING (not mounted)

執行復制：

RMAN> duplicate target database for standby from active database;

Starting Duplicate Db at 29-JUL-16
using target database control file instead of recovery catalog
allocated channel: ORA_AUX_DISK_1
channel ORA_AUX_DISK_1: SID=10 device type=DISK

contents of Memory Script:
{
   backup as copy reuse
   targetfile  '/u01/app/oracle/product/11.2.0.4/dbs/orapwBEIJING' auxiliary format 
 '/u01/app/oracle/product/11.2.0.4/dbs/orapwGUOAN'   ;
}
executing Memory Script

Starting backup at 29-JUL-16
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=19 device type=DISK
Finished backup at 29-JUL-16

contents of Memory Script:
{
   backup as copy current controlfile for standby auxiliary format  '/u01/app/oracle/oradata/GUOAN/control01.ctl';
   restore clone controlfile to  '/u01/app/oracle/oradata/GUOAN/control02.ctl' from 
 '/u01/app/oracle/oradata/GUOAN/control01.ctl';
}
executing Memory Script

Starting backup at 29-JUL-16
using channel ORA_DISK_1
channel ORA_DISK_1: starting datafile copy
copying standby control file
output file name=/u01/app/oracle/product/11.2.0.4/dbs/snapcf_BEIJING.f tag=TAG20160729T094647 RECID=1 STAMP=918467209
channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:03
Finished backup at 29-JUL-16

Starting restore at 29-JUL-16
using channel ORA_AUX_DISK_1

channel ORA_AUX_DISK_1: copied control file copy
Finished restore at 29-JUL-16

contents of Memory Script:
{
   sql clone 'alter database mount standby database';
}
executing Memory Script

sql statement: alter database mount standby database

contents of Memory Script:
{
   set newname for tempfile  1 to 
 "/u01/app/oracle/oradata/GUOAN/temp01.dbf";
   switch clone tempfile all;
   set newname for datafile  1 to 
 "/u01/app/oracle/oradata/GUOAN/system01.dbf";
   set newname for datafile  2 to 
 "/u01/app/oracle/oradata/GUOAN/sysaux01.dbf";
   set newname for datafile  3 to 
 "/u01/app/oracle/oradata/GUOAN/undotbs01.dbf";
   set newname for datafile  4 to 
 "/u01/app/oracle/oradata/GUOAN/users01.dbf";
   backup as copy reuse
   datafile  1 auxiliary format 
 "/u01/app/oracle/oradata/GUOAN/system01.dbf"   datafile 
 2 auxiliary format 
 "/u01/app/oracle/oradata/GUOAN/sysaux01.dbf"   datafile 
 3 auxiliary format 
 "/u01/app/oracle/oradata/GUOAN/undotbs01.dbf"   datafile 
 4 auxiliary format 
 "/u01/app/oracle/oradata/GUOAN/users01.dbf"   ;
   sql 'alter system archive log current';
}
executing Memory Script

executing command: SET NEWNAME

renamed tempfile 1 to /u01/app/oracle/oradata/GUOAN/temp01.dbf in control file

executing command: SET NEWNAME

executing command: SET NEWNAME

executing command: SET NEWNAME

executing command: SET NEWNAME

Starting backup at 29-JUL-16
using channel ORA_DISK_1
channel ORA_DISK_1: starting datafile copy
input datafile file number=00001 name=/u01/app/oracle/oradata/BEIJING/system01.dbf
output file name=/u01/app/oracle/oradata/GUOAN/system01.dbf tag=TAG20160729T094657
channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:25
channel ORA_DISK_1: starting datafile copy
input datafile file number=00002 name=/u01/app/oracle/oradata/BEIJING/sysaux01.dbf
output file name=/u01/app/oracle/oradata/GUOAN/sysaux01.dbf tag=TAG20160729T094657
channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:15
channel ORA_DISK_1: starting datafile copy
input datafile file number=00003 name=/u01/app/oracle/oradata/BEIJING/undotbs01.dbf
output file name=/u01/app/oracle/oradata/GUOAN/undotbs01.dbf tag=TAG20160729T094657
channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:15
channel ORA_DISK_1: starting datafile copy
input datafile file number=00004 name=/u01/app/oracle/oradata/BEIJING/users01.dbf
output file name=/u01/app/oracle/oradata/GUOAN/users01.dbf tag=TAG20160729T094657
channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:07
Finished backup at 29-JUL-16

sql statement: alter system archive log current

contents of Memory Script:
{
   switch clone datafile all;
}
executing Memory Script

datafile 1 switched to datafile copy
input datafile copy RECID=1 STAMP=918381060 file name=/u01/app/oracle/oradata/GUOAN/system01.dbf
datafile 2 switched to datafile copy
input datafile copy RECID=2 STAMP=918381060 file name=/u01/app/oracle/oradata/GUOAN/sysaux01.dbf
datafile 3 switched to datafile copy
input datafile copy RECID=3 STAMP=918381060 file name=/u01/app/oracle/oradata/GUOAN/undotbs01.dbf
datafile 4 switched to datafile copy
input datafile copy RECID=4 STAMP=918381060 file name=/u01/app/oracle/oradata/GUOAN/users01.dbf
Finished Duplicate Db at 29-JUL-16

回顯所使用的檔案傳輸指令碼和過程。

此時從備庫可以使用watch監控檔案傳輸進度：

watch ls
Every 2.0s: ls              Thu Jul 28 09:51:41 2016

control01.ctl
control02.ctl
redo01.log
redo02.log
redo03.log
redo04.log
redo05.log
redo06.log
redo07.log
sysaux01.dbf
system01.dbf
undotbs01.dbf
users01.dbf

傳輸完成，可以從備庫檢視，此時主備庫資料檔案、日誌檔案、引數檔案保持一致：

[email protected] GUOAN]$ ls -rlth
total 1.9G
-rw-r-----. 1 oracle oinstall 501M Jul 28 09:50 system01.dbf
-rw-r-----. 1 oracle oinstall 326M Jul 28 09:50 sysaux01.dbf
-rw-r-----. 1 oracle oinstall 201M Jul 28 09:50 undotbs01.dbf
-rw-r-----. 1 oracle oinstall 101M Jul 28 09:50 users01.dbf
-rw-r-----. 1 oracle oinstall 101M Jul 28 09:51 redo01.log
-rw-r-----. 1 oracle oinstall 101M Jul 28 09:51 redo02.log
-rw-r-----. 1 oracle oinstall 101M Jul 28 09:51 redo03.log
-rw-r-----. 1 oracle oinstall 101M Jul 28 09:51 redo04.log
-rw-r-----. 1 oracle oinstall 101M Jul 28 09:51 redo05.log
-rw-r-----. 1 oracle oinstall 101M Jul 28 09:51 redo06.log
-rw-r-----. 1 oracle oinstall 101M Jul 28 09:51 redo07.log
-rw-r-----. 1 oracle oinstall 9.1M Jul 28 09:51 control01.ctl
-rw-r-----. 1 oracle oinstall 9.1M Jul 28 09:51 control02.ctl

4.驗證主備庫狀態

此時檢視備庫狀態，處於MOUNT，角色是物理備庫：

SQL> select database_role, open_mode from v$database;
DATABASE_ROLE    OPEN_MODE
---------------- --------------------
PHYSICAL STANDBY MOUNTED

SQL> select status from v$instance;
STATUS
------------
MOUNTED

此時主庫狀態，處於OPEN，可讀寫：

[email protected]> select database_role, open_mode from v$database;
DATABASE_ROLE    OPEN_MODE
---------------- --------------------
PRIMARY          READ WRITE

[email protected]> select status from v$instance;
STATUS
------------
OPEN

5.切換ADG

開啟備庫實時應用：

SQL> recover managed standby database using current logfile disconnect from session;
Media recovery complete.

SQL> recover managed standby database cancel;
Media recovery complete.

SQL> alter database open;

SQL> select database_role, open_mode from v$database;
DATABASE_ROLE    OPEN_MODE
---------------- --------------------
PHYSICAL STANDBY READ ONLY

其中disconnect from session表示後臺執行，類似於shell的&。可以看出現在備庫處於READ ONLY狀態，不再是處於MOUNT不可使用的狀態，即現在可以執行只讀操作了。

繼續：

SQL> recover managed standby database using current logfile disconnect from session;
Media recovery complete.

SQL> select database_role, open_mode from v$database;
DATABASE_ROLE    OPEN_MODE
---------------- --------------------
PHYSICAL STANDBY READ ONLY WITH APPLY

此時資料庫狀態時READ ONLY WITH APPLY，即只讀且實時應用日誌，通常所說的ADG，Active Data Guard。

READ ONLY WITH APPLY表示備庫處於READ ONLY狀態的同時可以接收主庫傳過來的日誌檔案並進行恢復，以便備庫可以即時檢視到主庫的變化。

6.切換SNAPSHOT DATABASE

執行：

SQL> alter database recover managed standby database cancel;

SQL> alter database convert to snapshot standby;

SNAPSHOT的原理是基於閃回資料原理，此時備庫是可讀寫狀態，可以用這種真實的生產環境進行一些無法在測試環境做的實驗。使用完後，可以執行命令退回，SNAPSHOT期間對備庫做的所有變更都會還原：

SQL> alter database convert to physical standby;

SQL> alter database recover managed standby database disconnect;

7.切換主庫日誌

通過主庫手工切換日誌，來看看備庫是否實時接收應用了日誌，可以看出此時備庫的最新日誌SEQUENCE#是15號：

SYS@BEIJING> alter system archive log current; 
System altered.

SYS@BEIJING> select sequence#, first_time, next_time from v$archived_log order by sequence#;
 SEQUENCE# FIRST_TIME         NEXT_TIME
---------- ------------------ ------------------
        13 29-JUL-16          29-JUL-16
        13 29-JUL-16          29-JUL-16
        14 29-JUL-16          29-JUL-16
        14 29-JUL-16          29-JUL-16
        15 29-JUL-16          29-JUL-16
        15 29-JUL-16          29-JUL-16

此時檢視備庫，已經應用15號日誌：

SQL> select sequence#, first_time, next_time from v$archived_log order by sequence#;
 SEQUENCE# FIRST_TIME         NEXT_TIME
---------- ------------------ ------------------
        12 29-JUL-16       29-JUL-16
        13 29-JUL-16       29-JUL-16
        14 29-JUL-16       29-JUL-16
        15 29-JUL-16       29-JUL-16

8.設定歸檔日誌刪除策略

可以設定主庫的歸檔日誌應用至備庫後再刪除的策略，一方面保證了歸檔日誌傳輸接收，另一方面可以有效控制歸檔日誌檔案的產生量大小。預設是沒有任何刪除策略：

[[email protected] BEIJING]$ rman target /

Recovery Manager: Release 11.2.0.4.0 - Production on Fri Jul 29 10:10:55 2016
Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.
connected to target database: BEIJING (DBID=882855131)

RMAN> show all;

using target database control file instead of recovery catalog
RMAN configuration parameters for database with db_unique_name BEIJING are:
CONFIGURE RETENTION POLICY TO REDUNDANCY 1; # default
CONFIGURE BACKUP OPTIMIZATION OFF; # default
CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default
CONFIGURE CONTROLFILE AUTOBACKUP OFF; # default
CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '%F'; # default
CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default
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 COMPRESSION ALGORITHM 'BASIC' AS OF RELEASE 'DEFAULT' OPTIMIZE FOR LOAD TRUE ; # default
**CONFIGURE ARCHIVELOG DELETION POLICY TO NONE; # default**
CONFIGURE SNAPSHOT CONTROLFILE NAME TO '/u01/app/oracle/product/11.2.0.4/dbs/snapcf_BEIJING.f'; # default

執行：

RMAN> CONFIGURE ARCHIVELOG DELETION POLICY TO APPLIED ON ALL STANDBY;

new RMAN configuration parameters:
CONFIGURE ARCHIVELOG DELETION POLICY TO APPLIED ON ALL STANDBY;
new RMAN configuration parameters are successfully stored

再次檢視：

RMAN> show all;

RMAN configuration parameters for database with db_unique_name BEIJING are:
CONFIGURE RETENTION POLICY TO REDUNDANCY 1; # default
CONFIGURE BACKUP OPTIMIZATION OFF; # default
CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default
CONFIGURE CONTROLFILE AUTOBACKUP OFF; # default
CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '%F'; # default
CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default
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 COMPRESSION ALGORITHM 'BASIC' AS OF RELEASE 'DEFAULT' OPTIMIZE FOR LOAD TRUE ; # default
**CONFIGURE ARCHIVELOG DELETION POLICY TO APPLIED ON ALL STANDBY;**
CONFIGURE SNAPSHOT CONTROLFILE NAME TO '/u01/app/oracle/product/11.2.0.4/dbs/snapcf_BEIJING.f'; # default

9.總結
Data Guard的手工搭建方式，如果理清思路，還是比較清晰的，我最開始做的時候，由於監聽、連線串一系列問題，總是duplicate出錯，但手工方式好就好在可以讓你有除錯排查的機會，因為每一步手工操作都有他的意義，過程可逆，若是圖形操作，則相對封閉些。
另外，這裡只是DG搭建的最基礎方式，其實對於一套DG生產環境，還有很多預防性設定，之前參考過某些牛人的梳理，確實很詳細，有些內容自己還未掌握，還需要繼續學習。