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

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

We've seen Taf. Oracle's session can be automatically reconnected, it should be explained that this capability is based on the OCI, is a function of the OCI, JDBC Thin driver Invalid, because this driver is not built on the OCI library.

Although this feature originated in RAC, TAF is not limited to RAC, and the single instance, DG Environment can benefit from this. Oralce claims that its TAF ensures that user sessions are automatically transferred to another instance. This is really true, but it has water. To get a deeper understanding of TAF's capabilities, we're going to do a more granular experiment next.

1. TAF and Business

In a RAC environment, there are three ways to migrate a user session to another instance, including the Altersystem disconnect from session, shutdown, Dbms_service package, which are in fact consistent with the back-end mechanism and effect in three ways , there are three ways to migrate a session transparently or gracefully from one instance to another, and for this session, you don't even feel the migration of the sensation. Our experiment is done using the Alter system method, which has the following syntax:

Altersystem disconnect session [Post_transaction | immediate];

This command has two options, meaning the following:

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 are dependencies between different resources, such as using ASM as a stored database, and the DB instance is dependent on the ASM instance. This dependency is reflected in the ASM instance that must be started before the DB instance and must wait until the DB instance is closed before shutting down. The resource dependency is used to illustrate this relationship, defined by the required_resources parameter.

(3) Application profile (application description file)

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 dependencies, 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 is finally registered in OCR.

(4) Action program

Action program is an executable file that enables binary files and more shell scripts. The Oracle Cluster ha architecture uses this script to perform startup, shutdown, check, and transfer of resources. 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

When configured, there are two files that need to be created, application profile and Actionprofile, the former is a configuration file, and the latter is a shell script. But in fact, these two files do not need to be created manually, through this command can be automatically created, the reader only need to modify on the basis of it.

[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]#