Oracle ha High Availability specific explanation (ii, in-depth parsing of TAF, and HA framework)

Oracle HA High Availability specific explanation (one, client, server-side service specific explanation): Http://write.blog.csdn.net/postedit

We've seen Taf. Oracle's session can be connected on its own initiative, and it needs to be explained. This capability is based on the OCI and is a function of the OCI, and the JDBC Thin driver is invalid. Because such a drive is not built on the OCI library.

Although this feature originated in RAC. But Taf is not limited to RAC, single instance, DG Environment can enjoy this advantage.

Oralce claims that its TAF can ensure that the user session is actively transferred to another instance. This is true indeed. But it's got water.

In order to understand the ability of TAF deeply. We'll do a more elaborate experiment next.

1. TAF and Business

In a RAC environment, there are three ways to migrate a user session to an instance. Contains Altersystem disconnect from session, shutdown, Dbms_service package. The back-end mechanisms and effects of these three methods are in fact consistent, and the three ways to move a session transparently or gracefully from one instance to the next, even if it doesn't feel like such a migration occurs. We do this experiment with the alter system method, the syntax for this command is as follows:

Altersystem disconnect session [Post_transaction | immediate];

There are two options for this command, meaning the following, respectively:

Post_transaction: Means to disconnect an existing connection after the transaction has been committed;

Immediate: it means disconnecting immediately;

Oracle Cluster HA Framework
Terminology Introduction

(1) Resource (resources)

Resources require a CRS-managed entity called Resource.

Generally refers to a fire a group of processes.

(2) Resource Dependency (Resource dependent)

There is a dependency between different resources, for example, using ASM as a stored database, the DB instance relies on the ASM instance. Such a dependency body today the ASM instance must be started before the DB instance, and must wait until the DB instance shuts down.

and resource dependency is used to illustrate such relationships, through the definition of required_resources parameters.

(3) Application profile (application descriptive narrative document)

Application profile is a file that tells the CRS how to manage the application.

This file describes the properties of the application through the "attribute = value" format, such as resource scripting, resource dependency, resource prosecution frequency, and so on. When using Oraclecluster ha. The first step is to create this file, but this file is also a transition file, the content of the file will be in the final register to OCR.

(4) Action program

Action program is a executable file that enables binary files and many others to be shell scripts.

The Oracle Cluster ha architecture starts, shuts down, checks, and transfers resources through this script. This script must be able to handle the three parameters of start, stop, check.

(5) OCR

When configuring HA clusters for third-party applications, the contents of the application profile are finally registered in OCR.

Oracle Cluster reads the configuration content from OCR rather than application profile when working.

Configuration commands

(1) Crs_profile

There are two files that need to be created, application profile and Actionprofile. The former is a configuration file. The latter is a shell script. But in fact these two files do not need to be created manually, through this command can be created on their own initiative, the reader only need to change on its basis.

[Email protected]]#./crs_profile-h

Usage:crs_profile-create RESOURCE_NAME-T Application

[-dir Directory_path] [-A action_script] [-B Binary_pathname]

[-D description] [-H Hosting_members] [-R Required_resources]

[-L optional_resources] [-P Placement_policy]

[-O As=auto_start,ci=check_interval,ft=failure_threshold,

Fi=failure_interval,ra=restart_attempts,fd=failover_delay,

St=script_timeout,ap=active_placement,

Ut=uptime_threshold,rt=start_timeout,pt=stop_timeout] [-f] [-Q]

Crs_profile-create resource_name-i Template_file [-dir directory_path][-f] [-Q]

Crs_profile-delete resource_name [-dir directory_path] [-Q]

Crs_profile-print [resource_name [...] [-dir Directory_path] [-Q]

Crs_profile-template resource_name [-dir Directory_path] [-otemplate_file]

CRS_PROFILE-TEMPLATE-T application [-O template_file]

Crs_profile-update resource_name [-dir directory_path] [option ...] [-ooption,...] [-Q]

Crs_profile-validate resource_name [-dir directory_path] [-Q]

[Email protected] bin]#

Oracle ha High Availability specific explanation (ii, in-depth parsing of TAF, and HA framework)