Bhartendu Maheshwari wrote:
> Dear Hal, Frank, Oli and all,
>
> I understand what you all trying to say, I know this is not good way of
> designing, but we are planning for using the database for the keeping
> mobile transactions and at the same time we need to provided the HA
> solutions. The one solution i derive from the discussion that uses one
> server and multiple clients but the issue in this if the system in which
> database server was running get down the its all the way no use of HA
> and load balancing, since without data the other one can't do anything.
Here's an important question. What exactly is the thinking behind your
load balancing and HA requirements? The reason I'm asking this question
is because there's nuances to what high available means.
As an example, you've got redundant servers but they're all in the same
server room. A fire breaks out and kills everything. Not really HA IMO.
Or you have redundant servers in different rooms/buildings hooked up to
a NAS unit someplace else. A mover knocks the head off the ceiling fire
extinguisher and floods the place (I've seen this happen) killing the
NAS device. Again, not very HA. On the otherhand, if all your users are
housed in same building as the servers where a fire kills the servers
and also stops your users from doing any work, then it's not a problem.
The situation my company is in is we have users all over the U.S.
connecting to our app so to do HA, we needed to put duplicate servers
thousands of miles away from each other. That way, an earthquake in SF
or a terrorist attack in D.C. doesn't bring down our app. And since
traffic was load balanced between both locations, we needed
master-master replication which we had to code in at the app level.