Alejandro Vargas' Blog

  • March 19, 2008

Extended RAC on Pure Oracle Stack Summary

Alejandro Vargas
Technical Leader, ACS Global Delivery, Infrastructure & BigData

Extended RAC is a Tier 6 DRP technology that enable zero data loss in case of major disaster at a local site, and near 0 downtime if well configured and well managed.

It is an expensive technology because of the costs associated with the required infrastructure, dark fiber over long distances and redundant components on all hardware layers.

A strict change control procedure must be in place, with an identical test environment where all changes to the infrastructure and new code versions are carefully tested before implementation on the production site.

Oracle 11g provides new features that greatly help on implementing extended clusters, and makes it the version that best fit the challenge.

The syncronization between sites is obtained using ASM redundancy, reads are made locally at each site using ASM preferred mirror read feature, and in case of a local storage failure ASM fast mirrot resync make recovery much easier.
10g R2 and 11g Dataguard FSFO (Fast Start Failover) technology provide a similar level of protection at less cost and at greater distances, as it relays on TCP for communications, so it is convenient to consider it as an option when evaluating extended RAC for DRP.

This document: Extended RAC On Pure Oracle Stack Summary contains basic implementation guidelines.

More information can be found on these excellent documents:

Erik Peterson: Rac at a Distance

Clemens Bleile: Extended RAC POC

Christian Bilien:  Post on Extended RAC

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Comments ( 2 )
  • Dan Norris Wednesday, March 19, 2008
    How perfectly timely that you posted this today! The RAC SIG (http://www.oracleracsig.org/) is hosting a live webcast tomorrow morning (Thursday, March 20) on this very topic. The speaker is presenting a case study of an implementation he performed and it should be enlightening. The presentation's slides are already online on the website. If you (reader) want to attend, sign up with the RAC SIG and you'll find the login information on the Web Seminars page on the site. If you can't attend, look for the recorded version of the webcast sometime next week, with a link to the recording in the same place (the website) as soon as it is ready.
    Nice summary, Alejandro!
  • Miguel Palacios Thursday, March 27, 2008
    �If i use Oracle Clusterware and Oracle ASM version 11.1 or higher with Oracle Database 10g R2, can i take advantage of features of CRS and ASM 11.1 version?
    For example I would like to use: �11g ASM features �fast mirror resync� and �preferred mirror read� for extended RAC� to use it with Oracle Database 10g R2 Is it possible?
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