Infrastructure at your Service

Marc Wagner

Having multiple standby databases and cascading with dbvisit

Dbvisit standy is a disaster recovery solution that you will be able to use with Oracle standard edition. I have been working on a customer project where I had to setup a system having one primary and two standby databases. One of the standby database had to run with a gap of 24 hours. Knowing that flashback possibilities are very limited on standard edition, this would give customer the ability to extract and restore some data been wrongly lost following human errors.

The initial configuration would be the following one :

Database instance, db_name : MyDB
MyDB_02 (db_unique_name) primary database running on srv02 server.
MyDB_01 (db_unique_name) expected standby database running on srv01 server.
MyDB_03 (db_unique_name) expected standby database running on srv03 server.

The following DDC configuration file will be used :
MyDBSTD1 : Configuration file for first standby been synchronized every 10 minutes.
MyDBSTD2 : Configuration file for second standby been synchronized every 24 hours.

Let me walk you through the steps to setup such configuration. This article is not intended to show the whole process of implementing a dbvisit solution, but only the steps required to work with multiple standby. We will also talk about how we can implement cascaded standby and apply lag delay within dbvisit.

Recommendations

In order to limit the manual configuration changes in the DDC file after a switchover, it is recommended to use as much as possible same ORACLE_HOME, ARCHIVE Destination and DBVISIT home directory.

Creating MyDBSTD1 DDC configuration file

The first standby configuration file will be created and used between MyDB_03 (srv03) and MyDB_02 (srv02).

[email protected]:/u01/app/dbvisit/standby/ [MyDB] ./dbvctl -o setup


=========================================================

     Dbvisit Standby Database Technology (8.0.26_0_g3fdeaadd)
           http://www.dbvisit.com

=========================================================

=>dbvctl only needs to be run on the primary server.

Is this the primary server?  [Yes]:
The following Dbvisit Database configuration (DDC) file(s) found on this
server:

     DDC
     ===
1)   Create New DDC
2)   Cancel

Please enter choice [] : 1

Is this correct?  [Yes]:

...
...
...

Below are the list of configuration variables provided during the setup process:

Configuration Variable             Value Provided
======================             ==============
ORACLE_SID                         MyDB
ORACLE_HOME                        /opt/oracle/product/12.2.0

SOURCE                             srv02
ARCHSOURCE                         /u03/app/oracle/dbvisit_arch/MyDB
RAC_DR                             N
USE_SSH                            N
DESTINATION                        srv03
NETPORT                            7890
DBVISIT_BASE_DR                    /u01/app/dbvisit
ORACLE_HOME_DR                     /u01/app/oracle/product/12.2.0.1/dbhome_1
DB_UNIQUE_NAME_DR                  MyDB_03
ARCHDEST                           /u03/app/oracle/dbvisit_arch/MyDB
ORACLE_SID_DR                      MyDB
ENV_FILE                           MyDBSTD1

Are these variables correct?  [Yes]:

>>> Dbvisit Database configuration (DDC) file MyDBSTD1 created.

>>> Dbvisit Database repository (DDR) MyDB created.
   Repository Version          8.4
   Software Version            8.4
   Repository Status           VALID


Do you want to enter license key for the newly created Dbvisit Database configuration (DDC) file?  [Yes]:

Enter license key and press Enter: []: XXXXXXXXXXXXXXXXXXXXXXXXXXX
>>> Dbvisit Standby License
License Key     : XXXXXXXXXXXXXXXXXXXXXXXXXXX
customer_number : XXXXXX
dbname          : MyDB
expiry_date     : 2099-05-06
product_id      : 8
sequence        : 1
status          : VALID
updated         : YES

PID:423545
TRACE:dbvisit_install.log

Synchronizing both MyDB_02 and MyDB_03

Shippping logs from primary to standby

[email protected]:/u01/app/dbvisit/standby/ [rdbms12201] ./dbvctl -d MyDBSTD1
=============================================================
Dbvisit Standby Database Technology (8.0.26_0_g3fdeaadd) (pid 326409)
dbvctl started on srv02: Mon May 20 16:29:14 2019
=============================================================

>>> Obtaining information from standby database (RUN_INSPECT=Y)... done
    Thread: 1 Archive log gap: 30. Transfer log gap: 58080
>>> Sending heartbeat message... skipped
>>> First time Dbvisit Standby runs, Dbvisit Standby configuration will be copied to
    srv03...
>>> Transferring Log file(s) from MyDB on srv02 to srv03 for thread 1:

    thread 1 sequence 58051 (1_58051_987102791.dbf)
    thread 1 sequence 58052 (1_58052_987102791.dbf)
...
...
...
    thread 1 sequence 58079 (1_58079_987102791.dbf)
    thread 1 sequence 58080 (1_58080_987102791.dbf)

=============================================================
dbvctl ended on srv02: Mon May 20 16:30:50 2019
=============================================================

Applying log on standby database

[email protected]:/u01/app/dbvisit/standby/ [MyDB] ./dbvctl -d MyDBSTD1
=============================================================
Dbvisit Standby Database Technology (8.0.26_0_g3fdeaadd) (pid 21504)
dbvctl started on srv03: Mon May 20 16:33:42 2019
=============================================================

>>> Sending heartbeat message... skipped

>>> Applying Log file(s) from srv02 to MyDB on srv03:

    thread 1 sequence 58051 (1_58051_987102791.arc)
    thread 1 sequence 58052 (1_58052_987102791.arc)
...
...
...
    thread 1 sequence 58079 (1_58079_987102791.arc)
    thread 1 sequence 58080 (1_58080_987102791.arc)
    Last applied log(s):
    thread 1 sequence 58080

    Next SCN required for recovery 49719323442 generated at 2019-05-20:16:27:09 +02:00.
    Next required log thread 1 sequence 58081

=============================================================
dbvctl ended on srv03: Mon May 20 16:36:52 2019
=============================================================

Running a gap report

[email protected]:/u01/app/dbvisit/standby/ [MyDB] ./dbvctl -d MyDBSTD1 -i
=============================================================
Dbvisit Standby Database Technology (8.0.26_0_g3fdeaadd) (pid 335068)
dbvctl started on srv02: Mon May 20 16:37:53 2019
=============================================================


Dbvisit Standby log gap report for MyDB thread 1 at 201905201637:
-------------------------------------------------------------
Destination database on srv03 is at sequence: 58081.
Source database on srv02 is at log sequence: 58082.
Source database on srv02 is at archived log sequence: 58081.
Dbvisit Standby last transfer log sequence: 58081.
Dbvisit Standby last transfer at: 2019-05-20 16:37:36.

Archive log gap for thread 1:  0.
Transfer log gap for thread 1: 0.
Standby database time lag (DAYS-HH:MI:SS): +00:00:01.


=============================================================
dbvctl ended on srv02: Mon May 20 16:37:57 2019
=============================================================

Switchover to srv03

At that time in the project we did a switchover to the newly created srv03 in order to test its stability. The switchover has been performed as described below, but this step is not mandatory when implementing several standby databases. As best practices, we will always test the first configuration by running a switchover before moving forward.

[email protected]:/u01/app/dbvisit/standby/ [MyDB] ./dbvctl -d MyDBSTD1 -o switchover
=============================================================
Dbvisit Standby Database Technology (8.0.26_0_g3fdeaadd) (pid 12196)
dbvctl started on srv02: Tue May 28 00:07:34 2019
=============================================================

>>> Starting Switchover between srv02 and srv03

Running pre-checks       ... done
Pre processing           ... done
Processing primary       ... done
Processing standby       ... done
Converting standby       ... done
Converting primary       ... done
Completing               ... done
Synchronizing            ... done
Post processing          ... done

>>> Graceful switchover completed.
    Primary Database Server: srv03
    Standby Database Server: srv02

>>> Dbvisit Standby can be run as per normal:
    dbvctl -d MyDBSTD1


PID:12196
TRACE:12196_dbvctl_switchover_MyDBSTD1_201905280007.trc

=============================================================
dbvctl ended on srv02: Tue May 28 00:13:31 2019
=============================================================

srv03 is now the new primary and srv02 a new standby database.

Creating MyDBSTD2 DDC configuration file

Once myDB_01 standby database is up and running, we can create its related DDC configuration file. To do so, we simply copy previous DDC configuration file, MyDBSTD1, and update it as needed.

I first transferred the file from current primary srv03 to new standby server srv01 :

[email protected]:/u01/app/dbvisit/standby/conf/ [MyDB] scp dbv_MyDBSTD1.env [email protected]:$PWD
dbv_MyDBSTD1.env		100% 	23KB 	22.7KB/s 		00:00

I copied it into the new DDC configuration file name :

[email protected]:/u01/app/dbvisit/standby/conf/ [MyDB] cp dbv_MyDBSTD1.env dbv_MyDBSTD2.env

I updated new DDC configuration accordingly to have :

  • DESTINATION as srv01 instead of srv02
  • DB_UNIQUE_NAME_DR as MyDB_01 instead of MyDB_02
  • MAILCFG to see the alerts coming from STD2 configuration.

The primary will remain the same : srv03.

[email protected]:/u01/app/dbvisit/standby/conf/ [MyDB] vi dbv_MyDBSTD2.env

[email protected]:/u01/app/dbvisit/standby/conf/ [MyDB] diff dbv_MyDBSTD1.env dbv_MyDBSTD2.env
86c86
DESTINATION = srv02
---
DESTINATION = srv01
93c93
DB_UNIQUE_NAME_DR = MyDB
---
DB_UNIQUE_NAME_DR = MyDB_01
135,136c135,136
MAILCFG_FROM = [email protected] MAILCFG_FROM_DR = [email protected]
---
MAILCFG_FROM = [email protected]
MAILCFG_FROM_DR = [email protected]

In case the ORACLE_HOME and ARCHIVE destination are not the same, these parameters will have to be updated as well.

Synchronizing both MyDB_03 and MyDB_01

Shippping logs from primary to standby

[email protected]:/u01/app/dbvisit/standby/ [MyDB] ./dbvctl -d MyDBSTD2
=============================================================
Dbvisit Standby Database Technology (8.0.26_0_g3fdeaadd) (pid 25914)
dbvctl started on srv03: Wed Jun  5 20:32:09 2019
=============================================================

>>> Obtaining information from standby database (RUN_INSPECT=Y)... done
    Thread: 1 Archive log gap: 383. Transfer log gap: 67385
>>> Sending heartbeat message... done
>>> First time Dbvisit Standby runs, Dbvisit Standby configuration will be copied to
    srv01...
>>> Transferring Log file(s) from MyDB on srv03 to srv01 for thread 1:

    thread 1 sequence 67003 (o1_mf_1_67003_ghgwj0z2_.arc)
    thread 1 sequence 67004 (o1_mf_1_67004_ghgwmj1w_.arc)
...
...
...
    thread 1 sequence 67384 (o1_mf_1_67384_ghj2fbgj_.arc)
    thread 1 sequence 67385 (o1_mf_1_67385_ghj2g883_.arc)

=============================================================
dbvctl ended on srv03: Wed Jun  5 20:42:05 2019
=============================================================

Applying log on standby database

[email protected]:/u01/app/dbvisit/standby/ [MyDB] ./dbvctl -d MyDBSTD2
=============================================================
Dbvisit Standby Database Technology (8.0.26_0_g3fdeaadd) (pid 69764)
dbvctl started on srv01: Wed Jun  5 20:42:45 2019
=============================================================

>>> Sending heartbeat message... done

>>> Applying Log file(s) from srv03 to MyDB on srv01:

    thread 1 sequence 67003 (1_67003_987102791.arc)
    thread 1 sequence 67004 (1_67004_987102791.arc)
...
...
...
    thread 1 sequence 67384 (1_67384_987102791.arc)
    thread 1 sequence 67385 (1_67385_987102791.arc)
    Last applied log(s):
    thread 1 sequence 67385

    Next SCN required for recovery 50112484332 generated at 2019-06-05:20:28:24 +02:00.
    Next required log thread 1 sequence 67386

>>> Dbvisit Archive Management Module (AMM)

    Config: number of archives to keep      = 0
    Config: number of days to keep archives = 3
    Config: diskspace full threshold        = 80%
==========

Processing /u03/app/oracle/dbvisit_arch/MyDB...
    Archive log dir: /u03/app/oracle/dbvisit_arch/MyDB
    Total number of archive files   : 383
    Number of archive logs deleted = 0
    Current Disk percent full       : 8%

=============================================================
dbvctl ended on srv01: Wed Jun  5 21:16:30 2019
=============================================================

Running a gap report

[email protected]:/u01/app/dbvisit/standby/ [MyDB] ./dbvctl -d MyDBSTD2 -i
=============================================================
Dbvisit Standby Database Technology (8.0.26_0_g3fdeaadd) (pid 44143)
dbvctl started on srv03: Wed Jun  5 21:17:03 2019
=============================================================


Dbvisit Standby log gap report for MyDB_03 thread 1 at 201906052117:
-------------------------------------------------------------
Destination database on srv01 is at sequence: 67385.
Source database on srv03 is at log sequence: 67387.
Source database on srv03 is at archived log sequence: 67386.
Dbvisit Standby last transfer log sequence: 67385.
Dbvisit Standby last transfer at: 2019-06-05 20:42:05.

Archive log gap for thread 1:  1.
Transfer log gap for thread 1: 1.
Standby database time lag (DAYS-HH:MI:SS): +00:48:41.

Switchover to srv01

Now we are having both srv01 and srv02 standby databases up and running and connected with current srv03 primary database. Let’s switchover to srv01 and see what would be the required steps. After each switchover the other standby DDC configuration files will have to be manually updated.

Checking srv03 and srv02 are synchronized

Both srv03 and srv02 databases should be in sync otherwise ship and apply archive logs.

[email protected]:/u01/app/dbvisit/standby/ [MyDB] ./dbvctl -d MyDBSTD1 -i
=============================================================
Dbvisit Standby Database Technology (8.0.26_0_g3fdeaadd) (pid 93307)
dbvctl started on srv03: Wed Jun  5 21:27:02 2019
=============================================================


Dbvisit Standby log gap report for MyDB_03 thread 1 at 201906052127:
-------------------------------------------------------------
Destination database on srv02 is at sequence: 67386.
Source database on srv03 is at log sequence: 67387.
Source database on srv03 is at archived log sequence: 67386.
Dbvisit Standby last transfer log sequence: 67386.
Dbvisit Standby last transfer at: 2019-06-05 21:24:47.

Archive log gap for thread 1:  0.
Transfer log gap for thread 1: 0.
Standby database time lag (DAYS-HH:MI:SS): +00:27:02.


=============================================================
dbvctl ended on srvxdb03: Wed Jun  5 21:27:08 2019
=============================================================

Checking srv03 and srv01 are synchronized

Both srv03 and srv01 databases should be in sync otherwise ship and apply archive logs.

[email protected]:/u01/app/dbvisit/standby/ [MyDB] ./dbvctl -d MyDBSTD2 -i
=============================================================
Dbvisit Standby Database Technology (8.0.26_0_g3fdeaadd) (pid 90871)
dbvctl started on srv03: Wed Jun  5 21:26:31 2019
=============================================================


Dbvisit Standby log gap report for MyDB_03 thread 1 at 201906052126:
-------------------------------------------------------------
Destination database on srv01 is at sequence: 67386.
Source database on srv03 is at log sequence: 67387.
Source database on srv03 is at archived log sequence: 67386.
Dbvisit Standby last transfer log sequence: 67386.
Dbvisit Standby last transfer at: 2019-06-05 21:26:02.

Archive log gap for thread 1:  0.
Transfer log gap for thread 1: 0.
Standby database time lag (DAYS-HH:MI:SS): +00:26:02.

Switchover to srv01

[email protected]:/u01/app/dbvisit/standby/ [MyDB] ./dbvctl -d MyDBSTD2 -o switchover
=============================================================
Dbvisit Standby Database Technology (8.0.26_0_g3fdeaadd) (pid 20334)
dbvctl started on srv03: Wed Jun  5 21:31:56 2019
=============================================================

>>> Starting Switchover between srv03 and srv01

Running pre-checks       ... done
Pre processing           ... done
Processing primary       ... done
Processing standby       ... done
Converting standby       ... done
Converting primary       ... done
Completing               ... done
Synchronizing            ... done
Post processing          ... done

>>> Graceful switchover completed.
    Primary Database Server: srv01
    Standby Database Server: srv03

>>> Dbvisit Standby can be run as per normal:
    dbvctl -d MyDBSTD2


PID:20334
TRACE:20334_dbvctl_switchover_MyDBSTD2_201906052131.trc

=============================================================
dbvctl ended on srv03: Wed Jun  5 21:37:40 2019
=============================================================

Attach srv02 to srv01 (new primary)

Previously to the switchover :

  • srv03 and srv01 was using MyDBSTD2 DDC configuration file
  • srv03 and srv02 was using MyDBSTD1 DDC configuration file

srv02 standby database needs now to be attach to new primary srv01. For this we will copy the MyDBSTD1 DDC configuration file from srv02 to srv01 as it is the first time srv01 is primary. Otherwise, we would only need to update accordingly the already existing file.

I have been transferring the DDC file :

[email protected]:/u01/app/dbvisit/standby/conf/ [MyDB] scp dbv_MyDBSTD1.env [email protected]:$PWD
dbv_MyDBSTD1.env    100%   23KB  14.8MB/s   00:00

MyDBSTD1 configuration file has been updated accordingly to reflect new changes and configuration :

  • SOURCE needs to be replaced from srv03 to srv01
  • DESTINATION will remain srv02
  • DB_UNIQUE_NAME needs to be replaced fromMyDB_03 to MyDB_01
  • DB_UNIQUE_NAME_DR will remain MyDB_02
[email protected]:/u01/app/dbvisit/standby/conf/ [MyDB] vi dbv_MyDBSTD1.env

[email protected]:/u01/app/dbvisit/standby/conf/ [MyDB] grep ^SOURCE dbv_MyDBSTD1.env
SOURCE = srv01

[email protected]:/u01/app/dbvisit/standby/conf/ [MyDB] grep DB_UNIQUE_NAME dbv_MyDBSTD1.env
# DB_UNIQUE_NAME      - Primary database db_unique_name
DB_UNIQUE_NAME = MyDB_01
# DB_UNIQUE_NAME_DR   - Standby database db_unique_name
DB_UNIQUE_NAME_DR = MyDB_02

Checking that databases are all synchronized

After performing several switch logfile on the primary in order to generate archive logs, I transferred and applied needed archive log files on both srv02 and srv03 standby databases. I made sure both are synchronized.

srv01 and srv03 databases :

[email protected]:/u01/app/dbvisit/standby/ [MyDB] ./dbvctl -d MyDBSTD2 -i
=============================================================
Dbvisit Standby Database Technology (8.0.26_0_g3fdeaadd) (pid 98156)
dbvctl started on srv01: Wed Jun  5 21:52:08 2019
=============================================================


Dbvisit Standby log gap report for MyDB_01 thread 1 at 201906052152:
-------------------------------------------------------------
Destination database on srv03 is at sequence: 67413.
Source database on srv01 is at log sequence: 67414.
Source database on srv01 is at archived log sequence: 67413.
Dbvisit Standby last transfer log sequence: 67413.
Dbvisit Standby last transfer at: 2019-06-05 21:51:13.

Archive log gap for thread 1:  0.
Transfer log gap for thread 1: 0.
Standby database time lag (DAYS-HH:MI:SS): +00:00:00.


=============================================================
dbvctl ended on srv01: Wed Jun  5 21:52:18 2019
=============================================================

srv01 and srv02 databases :

[email protected]:/u01/app/dbvisit/standby/ [MyDB] ./dbvctl -d MyDBSTD1 -i
=============================================================
Dbvisit Standby Database Technology (8.0.26_0_g3fdeaadd) (pid 100393)
dbvctl started on srv01: Wed Jun  5 21:56:06 2019
=============================================================


Dbvisit Standby log gap report for MyDB_01 thread 1 at 201906052156:
-------------------------------------------------------------
Destination database on srv02 is at sequence: 67413.
Source database on srv01 is at log sequence: 67414.
Source database on srv01 is at archived log sequence: 67413.
Dbvisit Standby last transfer log sequence: 67413.
Dbvisit Standby last transfer at: 2019-06-05 21:55:22.

Archive log gap for thread 1:  0.
Transfer log gap for thread 1: 0.
Standby database time lag (DAYS-HH:MI:SS): +00:05:13.


=============================================================
dbvctl ended on srv01: Wed Jun  5 21:56:07 2019
=============================================================

Apply delay lag

MyDBSTD2 configuration should at the end have an apply lag of 24 hours. This can be achieved using APPLY_DELAY_LAG_MINUTES in the configuration. In order to test it, I have decided with customer to use 60 minutes delay.

Update MyDBSTD2 DDC configuration file

Following parameters have been updated in the configuration :
APPLY_DELAY_LAG_MINUTES = 60
DMN_MONITOR_INTERVAL_DR = 0
TRANSFER_LOG_GAP_THRESHOLD = 0
ARCHIVE_LOG_GAP_THRESHOLD = 60

APPLY_DELAY_LAG_MINUTES is the delay in minutes to take in account before applying the vector changes.
DMN_MONITOR_INTERVAL_DR is the interval in sec for log monitor schedule on destination. 0 mean deactivated.
TRANSFER_LOG_GAP_THRESHOLD is the difference allowed between the last archived sequence on the primary and the last sequence transferred to the standby server.
ARCHIVE_LOG_GAP_THRESHOLD is the difference allowed between the last archived sequence on the primary and the last applied sequence on the standby database before an alert is sent.

[email protected]:/u01/app/dbvisit/standby/conf/ [MyDB] cp dbv_MyDBSTD2.env dbv_MyDBSTD2.env.201906131343

[email protected]:/u01/app/dbvisit/standby/conf/ [MyDB] vi dbv_MyDBSTD2.env

[email protected]:/u01/app/dbvisit/standby/conf/ [MyDB] diff dbv_MyDBSTD2.env dbv_MyDBSTD2.env.201906131343
281c281
DMN_MONITOR_INTERVAL_DR = 0
---
DMN_MONITOR_INTERVAL_DR = 5
331c331
APPLY_DELAY_LAG_MINUTES = 60
---
APPLY_DELAY_LAG_MINUTES = 0
374c374
ARCHIVE_LOG_GAP_THRESHOLD = 60
---
ARCHIVE_LOG_GAP_THRESHOLD = 0

[email protected]:/u01/app/dbvisit/standby/conf/ [MyDB] grep ^TRANSFER_LOG_GAP_THRESHOLD dbv_MyDBSTD2.env
TRANSFER_LOG_GAP_THRESHOLD = 0

Report displayed with an apply delay lag been configured

When generating a report, we can see that there is no gap in the log transfer as the archive log would be transferred through the crontab every 10 minutes. On the other side, we can see that there is an expected delay of 60 minutes in applying the logs.

[email protected]:/u01/app/dbvisit/standby/ [MyDBTEST] ./dbvctl -d MyDBSTD2 -i
=============================================================
Dbvisit Standby Database Technology (8.0.26_0_g3fdeaadd) (pid 66003)
dbvctl started on srv03: Thu Jun 13 15:21:29 2019
=============================================================


Dbvisit Standby log gap report for MyDB_03 thread 1 at 201906131521:
-------------------------------------------------------------
Destination database on srv01 is at sequence: 73856.
Source database on srv03 is at log sequence: 73890.
Source database on srv03 is at archived log sequence: 73889.
Dbvisit Standby last transfer log sequence: 73889.
Dbvisit Standby last transfer at: 2019-06-13 15:20:15.

Archive log gap for thread 1:  33 (apply_delay_lag_minutes=60).
Transfer log gap for thread 1: 0.
Standby database time lag (DAYS-HH:MI:SS): +01:00:00.


=============================================================
dbvctl ended on srv03: Thu Jun 13 15:21:35 2019
=============================================================

Cascading standby database

What about cascading standby database? Cascading standby database is possible with dbvisit. We would be using a cascaded standby for a reporting server that needs to be updated less frequently or if we would like to unload the primary database in sending archive logs to multiple standby databases. The cascaded standby database will remain updated through the first standby. Cascading is possible since dbvisit version 8.

Following needs to be known :

  • Switchover will not be possible between the primary and the cascaded standby database.
  • The DDC configuration file between the first standby and the cascaded standby needs to have :
    • As SOURCE the first standby database
    • CASCADE parameter set to Y. This will be done automatically when creating the DDC configuration with dbvctl -o setup. From the traces you will see : >>> Source database is a standby database. CASCADE flag will be turned on.
    • ARCHDEST and ARCHSOURCE location on the first standby needs to have same values.

    The principle is then exactly the same, and running dbvctl -d from the first standby will ship the archive log to the second standby.

I had been running some tests in my lab.

Environment

DBVP is the primary server.
DBVS is the first standby server.
DBVS2 is the second cascaded server.

[email protected]:/u01/app/dbvisit/standby/ [DBVPDB] DBVPDB
********* dbi services Ltd. *********
STATUS                 : OPEN
DB_UNIQUE_NAME         : DBVPDB_SITE1
OPEN_MODE              : READ WRITE
LOG_MODE               : ARCHIVELOG
DATABASE_ROLE          : PRIMARY
FLASHBACK_ON           : NO
FORCE_LOGGING          : YES
VERSION                : 12.2.0.1.0
CDB Enabled            : NO
*************************************

[email protected]:/u01/app/dbvisit/standby/ [DBVPDB] DBVPDB
********* dbi services Ltd. *********
STATUS                 : MOUNTED
DB_UNIQUE_NAME         : DBVPDB_SITE2
OPEN_MODE              : MOUNTED
LOG_MODE               : ARCHIVELOG
DATABASE_ROLE          : PHYSICAL STANDBY
FLASHBACK_ON           : NO
FORCE_LOGGING          : YES
CDB Enabled            : NO
*************************************


[email protected]:/u01/app/dbvisit/standby/ [DBVPDB] DBVPDB
********* dbi services Ltd. *********
STATUS                 : MOUNTED
DB_UNIQUE_NAME         : DBVPDB_SITE3
OPEN_MODE              : MOUNTED
LOG_MODE               : ARCHIVELOG
DATABASE_ROLE          : PHYSICAL STANDBY
FLASHBACK_ON           : NO
FORCE_LOGGING          : YES
CDB Enabled            : NO
*************************************

Create cascaded DDC configuration file

The DDC configuration file will be created from the first standby node.
DBVS (first standby server) will be the SOURCE.
DBVS2 (cascaded standby server) will be the DESTINATION.

o[email protected]:/u01/app/dbvisit/standby/ [DBVPDB] ./dbvctl -o setup


=========================================================

     Dbvisit Standby Database Technology (8.0.20_0_g7e6bd51b)
           http://www.dbvisit.com

=========================================================

=>dbvctl only needs to be run on the primary server.

Is this the primary server?  [Yes]:
The following Dbvisit Database configuration (DDC) file(s) found on this
server:

     DDC
     ===
1)   Create New DDC
2)   DBVPDB
3)   DBVPDB_SITE1
4)   DBVPOMF_SITE1
5)   Cancel

Please enter choice [] : 1

Is this correct?  [Yes]:

...


Continue ?  [No]: yes

=========================================================
Dbvisit Standby setup begins.
=========================================================
The following Oracle instance(s) have been found on this server:

     SID            ORACLE_HOME
     ===            ===========
1)   rdbms12201     /u01/app/oracle/product/12.2.0/dbhome_1
2)   DBVPDB         /u01/app/oracle/product/12.2.0/dbhome_1
3)   DBVPOMF        /u01/app/oracle/product/12.2.0/dbhome_1
4)   DUP            /u01/app/oracle/product/12.2.0/dbhome_1
5)   Enter own ORACLE_SID and ORACLE_HOME
Please enter choice [] : 2

Is this correct?  [Yes]:
=>ORACLE_SID will be: DBVPDB
=>ORACLE_HOME will be: /u01/app/oracle/product/12.2.0/dbhome_1

>>> Source database is a standby database. CASCADE flag will be turned on.

Yes to continue or No to cancel setup?  [Yes]:

...
...
...

Below are the list of configuration variables provided during the setup process:

Configuration Variable             Value Provided
======================             ==============
ORACLE_SID                         DBVPDB
ORACLE_HOME                        /u01/app/oracle/product/12.2.0/dbhome_1

SOURCE                             DBVS
ARCHSOURCE                         /u90/dbvisit_arch/DBVPDB_SITE2
RAC_DR                             N
USE_SSH                            Y
DESTINATION                        DBVS2
NETPORT                            22
DBVISIT_BASE_DR                    /oracle/u01/app/dbvisit
ORACLE_HOME_DR                     /u01/app/oracle/product/12.2.0/dbhome_1
DB_UNIQUE_NAME_DR                  DBVPDB_SITE3
ARCHDEST                           /u90/dbvisit_arch/DBVPDB_SITE3
ORACLE_SID_DR                      DBVPDB
ENV_FILE                           DBVPDB_CASCADED

Are these variables correct?  [Yes]:

>>> Dbvisit Database configuration (DDC) file DBVPDB_CASCADED created.

>>> Dbvisit Database repository (DDR) already installed.
   Repository Version          8.3
   Software Version            8.3
   Repository Status           VALID


Do you want to enter license key for the newly created Dbvisit Database configuration (DDC) file?  [Yes]:

Enter license key and press Enter: []: 4jo6z-8aaai-u09b6-ijjxe-cxks5-1114a-ozfvp
[email protected]'s password:
>>> Dbvisit Standby License
License Key     : 4jo6z-8aaai-u09b6-ijjxe-cxks5-1114a-ozfvp
customer_number : 1
dbname          :
expiry_date     : 2019-05-29
product_id      : 8
sequence        : 1
status          : VALID
updated         : YES

PID:25571
TRACE:dbvisit_install.log

dbvisit software could see that the SOURCE is already a standby database. The software will then automatically configured the CASCADE flag to Y.

>>> Source database is a standby database. CASCADE flag will be turned on.
[email protected]:/u01/app/dbvisit/standby/conf/ [DBVPDB] grep CASCADE dbv_DBVPDB_CASCADED.env
# Variable: CASCADE
#      CASCADE = Y
CASCADE = Y

Synchronize first standby with primary

Ship archive log from primary to first standby
[email protected]:/u01/app/dbvisit/standby/ [DBVPDB] ./dbvctl -d DBVPDB
=============================================================
Dbvisit Standby Database Technology (8.0.20_0_g7e6bd51b) (pid 23506)
dbvctl started on DBVP: Wed May 15 01:24:55 2019
=============================================================

>>> Obtaining information from standby database (RUN_INSPECT=Y)... done
    Thread: 1 Archive log gap: 3. Transfer log gap: 3
>>> Transferring Log file(s) from DBVPDB on DBVP to DBVS for thread 1:

    thread 1 sequence 50 (o1_mf_1_50_gfpmk7sg_.arc)
    thread 1 sequence 51 (o1_mf_1_51_gfpmkc7p_.arc)
    thread 1 sequence 52 (o1_mf_1_52_gfpmkf7w_.arc)

=============================================================
dbvctl ended on DBVP: Wed May 15 01:25:06 2019
=============================================================
Apply archive log on first standby
[email protected]:/u01/app/dbvisit/standby/ [DBVPDB] ./dbvctl -d DBVPDB
=============================================================
Dbvisit Standby Database Technology (8.0.20_0_g7e6bd51b) (pid 27769)
dbvctl started on DBVS: Wed May 15 01:25:25 2019
=============================================================


>>> Applying Log file(s) from DBVP to DBVPDB on DBVS:

>>> No new logs to apply.
    Last applied log(s):
    thread 1 sequence 52

    Next SCN required for recovery 885547 generated at 2019-05-15:01:24:29 +02:00.
    Next required log thread 1 sequence 53

=============================================================
dbvctl ended on DBVS: Wed May 15 01:25:27 2019
=============================================================
Run a gap report
[email protected]:/u01/app/dbvisit/standby/ [DBVPDB] ./dbvctl -d DBVPDB -i
=============================================================
Dbvisit Standby Database Technology (8.0.20_0_g7e6bd51b) (pid 23625)
dbvctl started on DBVP: Wed May 15 01:25:55 2019
=============================================================


Dbvisit Standby log gap report for DBVPDB_SITE1 thread 1 at 201905150125:
-------------------------------------------------------------
Destination database on DBVS is at sequence: 52.
Source database on DBVP is at log sequence: 53.
Source database on DBVP is at archived log sequence: 52.
Dbvisit Standby last transfer log sequence: 52.
Dbvisit Standby last transfer at: 2019-05-15 01:25:06.

Archive log gap for thread 1:  0.
Transfer log gap for thread 1: 0.
Standby database time lag (DAYS-HH:MI:SS): +00:00:33.


=============================================================
dbvctl ended on DBVP: Wed May 15 01:25:58 2019
=============================================================

Synchronize cascaded standby with first standby

Ship archive log from first standby to cascaded standby
[email protected]:/u01/app/dbvisit/standby/ [DBVPDB] ./dbvctl -d DBVPDB_CASCADED
=============================================================
Dbvisit Standby Database Technology (8.0.20_0_g7e6bd51b) (pid 27965)
dbvctl started on DBVS: Wed May 15 01:26:41 2019
=============================================================

>>> Obtaining information from standby database (RUN_INSPECT=Y)... done
    Thread: 1 Archive log gap: 3. Transfer log gap: 3
>>> Transferring Log file(s) from DBVPDB on DBVS to DBVS2 for thread 1:

    thread 1 sequence 50 (1_50_979494498.arc)
    thread 1 sequence 51 (1_51_979494498.arc)
    thread 1 sequence 52 (1_52_979494498.arc)

=============================================================
dbvctl ended on DBVS: Wed May 15 01:26:49 2019
=============================================================
Apply archive log on cascaded standby
[email protected]:/u01/app/dbvisit/standby/ [DBVPDB] ./dbvctl -d DBVPDB_CASCADED
=============================================================
Dbvisit Standby Database Technology (8.0.20_0_g7e6bd51b) (pid 21118)
dbvctl started on DBVS2: Wed May 15 01:27:21 2019
=============================================================


>>> Applying Log file(s) from DBVS to DBVPDB on DBVS2:

    thread 1 sequence 50 (1_50_979494498.arc)
    thread 1 sequence 51 (1_51_979494498.arc)
    thread 1 sequence 52 (1_52_979494498.arc)
    Last applied log(s):
    thread 1 sequence 52

    Next SCN required for recovery 885547 generated at 2019-05-15:01:24:29 +02:00.
    Next required log thread 1 sequence 53

=============================================================
dbvctl ended on DBVS2: Wed May 15 01:27:33 2019
=============================================================
Run a gap report
[email protected]:/u01/app/dbvisit/standby/ [DBVPDB] ./dbvctl -d DBVPDB_CASCADED -i
=============================================================
Dbvisit Standby Database Technology (8.0.20_0_g7e6bd51b) (pid 28084)
dbvctl started on DBVS: Wed May 15 01:28:07 2019
=============================================================


Dbvisit Standby log gap report for DBVPDB_SITE2 thread 1 at 201905150128:
-------------------------------------------------------------
Destination database on DBVS2 is at sequence: 52.
Source database on DBVS is at applied log sequence: 52.
Dbvisit Standby last transfer log sequence: 52.
Dbvisit Standby last transfer at: 2019-05-15 01:26:49.

Archive log gap for thread 1:  0.
Transfer log gap for thread 1: 0.
Standby database time lag (DAYS-HH:MI:SS): +00:00:00.


=============================================================
dbvctl ended on DBVS: Wed May 15 01:28:11 2019
=============================================================

Conclusion

With dbvisit we are able to configure several standby databases, choose apply lag delay and also configure cascaded standby. The cons would be that the DDC configuration file needs to be manually adapted after each switchover.

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Marc Wagner
Marc Wagner

Consultant