Another issue I just thought of is that you would (well we would) need
to have significant bandwidth between the primnary and secondary sites
as the app servers hit the DBs pretty hard at startup. 200Mbps between
the sites would do it. Prehaps via VPN.
amigan wrote:
> Thank-you much Daniel. That's interesting. There are two touted
> advantages of active-active. One is that you can have a global load
> balancing - a DNS SOA which replies with the closest data center/web
> tier address to the client. The idea being that the end user gets a
> faster response via reduced latency to the web tier.
>
> If the DR site is actively running the app tier then you have better
> response time between app tier and web tier than if web tier has to
> interact with the primary site on another continent say. Sounds like
> the latency of reaching a primary Oracle database is just something
> that can't be avoided and you just have to work on prioritizing or
> accelerating that traffic as much as possible.
>
> The second advantage of active-active is faster fail-over time. No
> need to change BGP advertisements say as you might in a more standard
> primary/warm DR site setup.
>
> Michael
>
> DA Morgan wrote:
> > amigan wrote:
> > > Is it possible to have two active data centers each receiving database
> > > updates via web site and application at each respective site? Somehow
> > > for the two active data centers to replicate in the complimentary
> > > direction and survive the outage of one of the active data centers and
> > > retain data integrity? Thanks.
> >
> > You can use DataGuard or Streams or Change Data Capture (CDC) to
> > replicate between databases. You can build failover clusters with
> > application servers. But your web application can and should talk
> > to only one database instance. Let the database replicate itself
> > for high-availability.
> > --
> > Daniel Morgan
> > University of Washington
> > Puget Sound Oracle Users Group
Received on Wed Sep 20 2006 - 13:34:47 CDT
