PDU - Control Power & Remote Reboot In Server Rooms & Data Centers Using SNMP

What is a PDU?

If you work in any telecom or server room environment, and you're not currently using PDUs (Power Distribution Units), you should be. PDUs allow you to toggle power on and off to your network devices remotely. Think about all the times that all you had to do was reboot a rack-mounted server (or any other piece of equipment) to get it working again. It's an incredibly easy task, but you incur costs in the time it takes you to reach that equipment. It's much better to handle the same task remotely with a PDU.

Think of a PDU as a large power strip with built-in intelligence. When it's mounted on a standard 19" or 23" rack, you'll hear it referenced as a "switched rack PDU". You plug the PDU into your site power (AC and DC models are available), and then connect multiple devices (usually about eight) to the back of the PDU. Next, you'll plug some form of transport into the back of the PDU. This is usually LAN, serial, and/or dial-up. Alternative transports like serial and dial-up can be good in situations where LAN has failed and you need to reach the PDU remotely to issue a reboot command.

PDU (Power Distribution Unit) with SNMP
One example of a DC-powered PDU.

That's really all there is to it. Now, when a piece of equipment freezes up, you can simply issue a remote reboot command to your PDU, which will toggle power off to that device, then immediately turn it back on. That PDU just saved you a lot of time and effort traveling out to a telecom site or server room.

Look for a PDU with a web interface

When you're evaluating PDUs, it's best to find one that has a web interface. This makes it easy to issue a "turn on", "turn off", or "reboot" command from any PC on your network using just a web browser. All you have to do is type in the IP address of your PDU into your browser and press 'Return'. You login to your PDU with a username and password (an important feature for preventing unauthorized access to your site power control), and then issue your commands. You can also view the current state of all power output ports from the web interface.

Keep an eye on power-hungry server room & data center equipment

Some PDUs will even monitor the current flow going through each power output port. This is an invaluable feature when you want to track the power consumption to your sites. This tends to be important to people working in data centers and server rooms - especially in the modern world where "green" technology has become all the rage. Current monitoring is also important for PDUs when they'll be deployed in environments that must operate on battery backup power most or all of the time. You simply can't afford to have a power hog in those kinds of environments.

SNMP and the PDU make an excellent team...

SNMP is usually a technology reserved for RTU's and other remote monitoring gear, but it's important in the PDU world as well. If you're going to be deploying more than a few PDUs, they have to be able to integrate into your industry-standard alarm monitoring platform. Most of those are based on the SNMP protocol. If your PDU can output SNMP, it gives you a big leg up when you're trying to integrate it with your SNMP manager.

Integration of your PDUs with your SNMP manager offers several advantages. First, you're able to track the current state of each power output port, as well as the power input of the PDU. You can also track for PDU hardware failures and other "internal" alarms.

Even more importantly, an SNMP PDU can be remotely controlled via your SNMP manager. This means that you can set up a fully automatic server (or other equipment ) reboot/power cycling system.

If your SNMP manager receives a trap message from equipment that has jammed up (or, more likely, it can't get any kind of response from that device), it can automatically issue a power cycle command to the PDU. In this way, SNMP integration with your PDUs can eliminate the requirement for a human response entirely. Of course, a good SNMP manager and/or PDU will send you an alert describing the problem and the action that is automatically taken. That way, you can issue a manual PDU command or other adjustment that you feel it necessary.

Getting PDU functionality from your existing RTU
With the right accessory box, it is possible to convert your RTU to a power distribution unit. The RTU's native low-amp relays are used to control high-amp relays on the converter box.