Re: Running Oracle RAC 11g and Data Guard across two data centres

From: John Hurley <>
Date: Thu, 9 Jul 2009 08:21:32 -0700 (PDT)
Message-ID: <>

On Jul 8, 9:34 pm, DG problem <> wrote:
> Apologies if this question is too general or not enough information
> given.
> What is the best way to configure a data warehouse and an OLTP system
> (OLTP system would generate about 60Gb of archive logs a day at about
> 150 commits per second) on the following hardware?
> Two separate data centres with a fibre link.
> Each data centre has two boxes (each box has a Sun M4000, 2 x quad
> core 2.4GHz) and 35Tb of storage.
> Running Oracle 11g with RAC and Data Guard.
> The data warehouse would be a copy of the OLTP data and would
> obviously grow as the OLTP database grows. OLTP data would be archived
> to the data warehouse.
> The current proposal is to run RAC across both boxes in one data
> centre. ie, have both databases running on both boxes with RAC and
> then to use data guard for the standbys in the other data centre.
> However, this seems far from optimal to me. Wouldn't it be better to
> run RAC across both data centres?
> Does it make sense to use RAC and data guard together as mentioned
> above?
> If RAC was used across both data centres does this mean that:
> 1) You can achieve 100% uptime even if one data centre shuts down or
> suffers catastrophic failure?
> 2) You can achieve 100% uptime while patching/upgrading one instance
> at a time?
> 3) You woudln't need to use data guard as RAC provides fail over?
> If RAC is only run in one data centre, and that data centre goes down,
> then you will have down time while failing over to the standby
> databases in the other data centre and if you are not running data
> guard in maximum protection (due to possible performance issues caused
> by latency), you could potentially lose data? I realise that with a
> fast high bandwidth connection, data guard will run in maximum
> protection with minimum performance hit, however, politics sometimes
> cuts costs by cutting bandwidth :(
> I realise that there are lots of new features in data guard 11g, eg
> standby databases can be open for queries. Are there any other
> features that could be used?
> Any other tips or criticisms?
> Thanks

Try doing some research on geo clusters and RAC ... lots of complications and problems when trying to run an application on RAC clusters more than "so far" apart ... Received on Thu Jul 09 2009 - 10:21:32 CDT

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