Purpose

ardServerRoomProbe or ASRP has for purpose:

• Provide the INFRA team engineers with informations related to the server room status (not the servers themselves, they already have this)
• Provide the following info:
  • Current and historical temperature (use 2~3%20 temp probes) - 3 probes %20 average
  • Current and historical humidity - drop, too annoying
• Information should be made available :
  • Database (on the server piloting the ASRP) [HIGH] - drop it, the Nagios takes care.
  • SNMP [MED] - done!
  • Web interface [MED] - drop, Nagios job
  • Mail on alert [HIGH] - drop, Nagios job

Inspiration can be taken from http://www.industrialethernet.com/sp8.html

Pictures

Tadaaaa ♪ The boxed version, bling-bling flavor. 3 probes, total less than 40 Euro.

Material

• Arduino card : no special things needed, so even a Tiny would fit. However since permanent USB connection is required and size doesn't matter, let's roll with the Arduino 2009.
• LM35 temperature probes x3 (150 JPY x3) http://akizukidenshi.com/catalog/g/gI-00116/
  • Or LM61 http://akizukidenshi.com/catalog/g/gI-02753/
• Humidity probe x1 (500 JPY) http://akizukidenshi.com/catalog/g/gI-00117/
• Leds : power x1, now probing x1
• Box, resistors, USB cable,...
• On-box display ? http://akizukidenshi.com/catalog/g/gP-02919/

Code

SNMP Agent

See here SNMP agent in C#. I won't disclose the real version of the software, but I can show the tests we made before moving to the real job.

Arduino probing code

It has 3 sensors (pin analog 0 to 2) plus a blink led on digital 12.
It polls all the sensors every 3 seconds, store the SENSOR_AVERAGE latest results in an array and return the average per sensor. Up to the tests I've done now, it's quite nice results...

Source SVN

#define PIN_LED 12
 
#define SENSOR_COUNT 3
#define SENSOR_AVERAGE 6
 
long mSavedValues[SENSOR_COUNT][SENSOR_AVERAGE];
int mRound = 0;
 
void setup()                    // run once, when the sketch starts
{
  pinMode(PIN_LED, OUTPUT);
  Serial.begin(9600); // begin serial
 
  //init table of values
  for (int i =0; i < SENSOR_COUNT; i%20%20){
    for (int j = 0; j < SENSOR_AVERAGE; j%20%20){
      mSavedValues[i][j] = 0;
    }
  }
}
 
long vVal = 0;
long vValScaled = 0;
char vMessage[50];
char vBuffer[20];
 
void loop()                     // run over and over again
{
 
  //start reading
  digitalWrite(PIN_LED, HIGH);
 
  //read values and store
  for (int i =0; i < SENSOR_COUNT; i%20%20){
    vVal = analogRead(i);
    vValScaled = ((long)5*vVal*(long)100/(long)1024);         //convert voltage to temperature
    mSavedValues[i][mRound] = vValScaled;
  }
 
  mRound = (mRound %20 1) % SENSOR_AVERAGE;
 
 
  //calculate average
  for (int i =0; i < SENSOR_COUNT; i%20%20){
    //reset message buffer
    vMessage[0] = 0;
    vVal = 0;
    for (int j = 0; j < SENSOR_AVERAGE; j%20%20){
      vVal %20= mSavedValues[i][j];
    }
    vVal = vVal / SENSOR_AVERAGE;
 
    itoa(i, vBuffer, 10);
    strcat(vMessage,vBuffer);
    strcat(vMessage,"=");
    itoa(vVal, vBuffer, 10);
    strcat(vMessage,vBuffer);
    strcat(vMessage,",");
 
    Serial.print(vMessage);
  }
  Serial.println("");
 
  //end of read
  digitalWrite(PIN_LED, LOW);
 
 
  delay(3000);
}