Re: Multiple Server Setup

[Jan Derfinak]

On Tue, 21 Sep 2010, Breandan Dezendorf wrote:

Hello.

> I'm trying to setup gnokii-smsd to handle my SMS traffic for a medium
> sized Nagios monitoring installation, and I have a question about
> architecture.  There are two servers setup to handle notifications,
> and only one has notifications enabled at a time.  Each server has a
> Nokia cell phone attached, and I'm able to send SMSs using the
> "standalone" gnokii.  I was careful to purchase two identical servers
> and two identical phones, so the config files match.
> 
> Ideally, I'd like to setup gnokii-smsd on each server, and have both
> instances point to the same database tables on a clustered DB server.
> This way, if Server A fails, Server B would be able to pick up where A
> left off, and any SMS messages that were about to be sent would then
> be sent from the other server.  I'm worried that the servers would

I think that you need a trigger which performs some action when server A
fails. I imagine three solutions:

1. You have only one instance of smsd active on both servers. When primary
server fails, you start smsd on backup server. It is the simlest solution but
the downside of this solution is that you cannot ensure that backup instance
is not activated by mistake.

2. You can use "phone" feature in smsd (-t parameter, see man). In this
case smsd on both servers must be configured with different "phone" in
config file and when adding sms to DB you must fill "phone" column with
primary phone number. Then both instances can be run simultaneously and
every instance care only about sms with its "phone". When primary server
fails you must update phone number in phone column for all unprocessed
sms and new sms must be added with backup phone number.
This is more complex solution and it can be tricky to setup client aplication.
It must be able to detect which phone active every time when inserting sms
to DB.

3. Use clustered environment. Configure smsd as in solution A and let
cluster software to care about smsd starting on every node. For me this
looks as the best solution.

jan


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