a previous post, I talked about the LoVoN project, an SMS-gateway running on a Raspberry Pi with an USB-modem. Well, could it be the Raspberry Pi is not quit suited for this task? While our setup has been running for more than 2 months, we suddenly found out, sms where send more than once. Strange behaviour that was not exactable. After excluding all possible errors, we finally managed to find out what was happening.
It seems that our Raspberry Pi running Mono, could handle things fast enough. Not a problem, we thought, because if the SMS is 5 minutes late, it ain't a big deal. But then we found the real problem. While the modem does hardware interrupts, our build-in smtp handler got interrupted too. Meaning that, before it could tell the other email-servers (in our case Google): OK got the email, they hang up. (right behaviour, because it sometimes took more than 2 minutes). Google in this case, assumes the email didn't get delivered, so it retried up to 4 times, although LoVoN actually did receive the email the very first time.
We couldn't let that happen, in a life production, so we decided to put the whole of LoVoN on a normal computer for now. Guess what, all problems are solved. We might look into the real problem, meaning, can't we get this to speed up, but for know we'll abandon the Raspberry Pi as the hardware running LoVoN. I'll keep you informed.