Lesson 10	Instantiating snapshot sites offline
Objective	Walk through the Steps to Create Snapshots Offline.

Steps to Create Database Snapshots Offline

In Oracle, snapshot deployment templates can be instantiated online or offline. Online instantiation allows a snapshot site to instantiate the template while connected to the target master site. The advantage to online instantiation is that the data will be very current. However, online instantiation requires that you have a dedicated connection to the master site. These connections can be of long duration, and they can cause severe network traffic and response-time problems across the network. To alleviate such network traffic, you can expand your replicated environment by using the offline instantiation procedure. In offline instantiation, Oracle invokes an export and creates an export file. This export file is then transferred to the new site, resulting in far less network traffic. Let us take a closer look at the offline instantiation process. This process uses the DBMS_OFFLINE_OG pre-defined package.
The seriers of images below takes you through the steps of offline instantiation.

Instantiate: To create a specific version of an object (such as a snapshot) based on a template and some specific variables.
Online instantiation: Creating snapshot templates in real time with a connection between the master and the remote sites.
Offline instantiation: Creating snapshot templates using export and import utilities. No connection is required between the master and the remote site during the process.

Offline snapshot instantiation

1) To begin the offline instantiation process, you must first call BEGIN_INSTANTIATION, pending the name and the destination.

2) You use the Oracle export utility to export the desired table.

3) After the export is complete, you call the RESUME_SUBSET_OF_MASTERS procedure to resume replication activities for the master sites

4) Transfer the export file from the master definition site to the new master site via FTP — 4) Now you transfer the export file from the master definition site to the new master site via FTP

5) Prepare the new site to import data from your export file — 5) Next, you are ready to prepare the new site to import data from your export file. To do this, you log into the remote site and call the BEGIN_LOAD procedure.

6) Import the data into the new site — 6) You now Import the data into the new site, using your export file as input.

7) After you have imported the export file, you call the END_LOAD procedure. This will prepare the site to resume normal replication — 7) After you have imported the export file, you call the END_LOAD procedure.
This will prepare the site to resume normal replication

8) final step is to formally complete the offline instantiation process — 8) The final step is to formally complete the offline instantiation process by calling the END_INSTANTIATION procedure. This will end the offline instantiation and resume normal replication activity at all master sites.

The next lesson describes another new snapshot feature.