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Introduction

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1.  Architecture Overview

The following diagram is a high level overview of the Dbvisit Standby version 8 architecture.


On this page:



1.1.  Dbvisit Standby Feature Summary


Dbvisit Standby functionality can be summarized as follows:

    • Archive log extraction from primary database
    • Secure transfer of archive logs between primary and standby servers
    • Apply of archive logs to the standby database
    • Easy role reversal (switchover) between primary and standby databases
    • Easy activation of a standby database in case of disaster
    • Full support for Oracle Real Application Clusters (RAC)
    • Support for one primary database having multiple standby databases
    • Recover standby database using a delay (LAG)
    • Recover standby to specified SCN or Timestamp
    • Archive logs compression during transfer
    • Archive log Management Module (AMM) 
    • Maintain archive logs on both primary and standby
    • Delete logs older than a specified time
    • Compress archive logs that have already been applied
    • Automated process to create the standby database (CSD)
    • Automated process to re-synchronize the standby database due to:
      • Unrecoverable Archive log gap
      • No-Logging operations 
    • Reporting options include:
      • Archive log transfer gap reporting
      • Archive log apply gap reporting
    • Command line interface (CLI) and Graphical User Interface (GUI) is available


We can summarise the core functionality of Dbvisit Standby into three key process:

1.2.  Log Extraction


Dbvisit Standby will extract the primary database archive logs from the database archive destination.
The following steps form part of the log extraction process:

  • The latest archive logs will be extracted to be shipped to the standby
  • A "logswitch" will be forced if no new logs were generated since last run
  • Logs will be compressed if compression option is selected
  • If configured, Dbvisit Standby can also manage the archive logs on the primary server; example purge logs older than specified time

1.3.  Transport


The second step in the process will be to copy these extracted archive logs to the standby site.  
This transfer process is initiated from the primary server and the transfer process is secure. 
The following steps form part of the log transfer process:

  • The latest archive logs will be transferred using the Dbvisit Network (Dbvnet) or SSH (Unix Only)
  • The connection between the primary and standby site is encrypted and secure by default
  • Archive logs will be transferred in compressed format if required
  • From version 7, Archive logs are renamed to a standard format as part of the transfer process and will be stored on the standby server in new naming convention (example thread#_sequence#_resetlogs_id.arc)
  • Checksum values are generated to ensure logs are transferred successfully
  • Dbvnet is making use of of port 7890 by default and this port should be open for communication (SSH is fully supported as communication method between Primary and Standby on UNIX based systems)

1.4.  Log Apply


The third step in the process is where Dbvisit Standby apply the transferred archive logs to the standby database.
The following steps form part of the log apply process:
  - On the Standby Server, Dbvisit Standby will pickup the transferred archive logs and apply them to the standby database
  - If configured, Dbvisit Standby can also manage the archive logs on the standby server; example purge logs older than specified time


The above is only a summary of the core functionality of Dbvisit Standby which is to extract, send and apply logs.  


2.  Dbvisit Standby Components


Dbvisit Standby refers to the product "Dbvisit Standby" and does not refer to the standby database or standby server.


The Dbvisit Standby environment consists of the following components:

Dbvnet

(Dbvisit Networking)


Dbvisit Standby Version 7 introduced a new component called Dbvnet.  
This component is responsible for the secure communication between the primary and standby systems. It consists of the following executable:

  • dbvnet - This is the main Dbvnet executable used to start the networking communication between the primary and standby server. 
    This component should run on both the primary and standby servers and is configured during the installation process.
  • SSH can still be used (instead of dbvnet) on UNIX based systems for communications.

Dbvserver

(Dbvisit Standby GUI)


This is a Web server that provides the web interface to Dbvisit. 
It consists of the following executable:

  • dbvserver - The main Dbvserver executable for the Dbvisit Web server, and is used to start/stop the Dbvisit Web server.

Dbvagent

(Dbvisit Agent)

The Dbvisit Agent is used to manage the Standby core background processes as well as managing the communication between the Dbvserver (Web based interface) and the Dbvisit Standby core.

  • dbvagent - The main Dbvisit Agent executable, and is used to start/stop the Dbvisit Agent.

Standby Core

(Dbvisit Standby Core and CLI)


Dbvisit Standby, also referred to as Standby, is the core of the Dbvisit Standby product. 
This consists of the following executables (commands):

  • dbvctl - The main Dbvisit Standby control utility (executable)

Dbvisit Database Configuration

(DDC file)

This is similar to the init.ora parameter file and contains the Dbvisit Standby settings for a specific primary and standby database pair. 

The DDC file is generated during setup for each database.

The DDC file should only be edited on the primary server.

Dbvisit Database Repository

(DDR)

This repository contains the Dbvisit Standby tables used to manage the standby process.

It is located outside the Oracle database in a small file under the DBVISIT_BASE/conf directory called .db example if DDC name is PROD the file name will be "prod.db"

The DDR is created during setup.

Dbvisit Standby trace files

Each time Dbvisit Standby executes, a trace file is generated. This trace file contains information about Dbvisit Standby processing and its environment.

When an alert or error notification is sent by Dbvisit Standby, the trace file will be attached to the email so that this can be forwarded to Dbvisit support if needed.

This trace file is used by the Dbvisit support team to diagnose issues.


Dbvisit Standby version 8 uses a slightly new directory structure compared to previous versions.  

The primary directory (DBVISIT_BASE) is by default id called "dbvisit" but it can be adjusted during installation - it contains five sub-directories, providing a logical grouping of the Dbvisit Standby components:

  • Dbvnet - Networking
  • Dbvserver - GUI
  • Standby for CLI and Core Standby functionality
  • Installer - used for installation configuration files


3.  Dbvisit Standby Directory Structure

The following directory structure is used by Dbvisit Standby version 8:

When Installing Dbvisit Standby version 8 it is important to take note of the directory structure.

The default installation location on Unix based systems are /usr/dbvisit and on Windows based systems: C:\Program Files\Dbvisit

The table below is an illustration of the full directory structure with all products installed.

It is however recommended that the Webserver component - Dbvserver not be installed on the database servers, but on a seperate system.


Unix Based Systems Windows Based Systems

Dbvisit Standby Core Installation (Dbvnet, Dbvagent, Standby Core - CLI)

/usr/dbvisit             
         ├── dbvagent    
         │   ├── conf    
         │   ├── doc     
         │   └── log     
         ├── dbvnet      
         │   ├── conf    
         │   ├── doc     
         │   ├── log     
         │   └── tmp     
         └── standby     
             ├── conf    
             ├── doc     
             ├── gs      
             ├── lib     
             ├── log     
             ├── pid     
             ├── support 
             ├── tmp     
             │   └── GS  
             └── trace   


Dbvisit Standby GUI (Dbvserver) installation only:

/usr/dbvisit   
          ├── dbvserver  
             ├── conf   
             ├── doc    
             ├── log    
             └── www    
    

Dbvisit Standby Core Installation (Dbvnet, Dbvagent, Standby Core - CLI)

C:\Program Files\Dbvisit             
                   ├── dbvagent   
                   │   ├── conf   
                   │   ├── doc    
                   │   └── log    
                   ├── dbvnet     
                   │   ├── conf   
                   │   ├── doc    
                   │   ├── log    
                   │   └── tmp    
                   └── standby    
                       ├── conf   
                       ├── doc    
                       ├── gs     
                       ├── lib    
                       ├── log    
                       ├── pid    
                       ├── support
                       ├── tmp    
                       │   └── GS 
                       └── trace  


Dbvisit Standby GUI (Dbvserver) installation only:

C:\Program Files\Dbvisit  
                   ├── dbvserver  
                      ├── conf   
                      ├── doc    
                      ├── log    
                      └── www    
                  




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