Networked Plug Socket

There’s an infrequently recurring problem with our home-made MythTV DVR that is, despite its rare occurrence, quite irritating.

Under certain circumstances that I haven’t been able to meticulously define, and when multiple tuner cards are simultaneously recording TV programmes, the machine can hang when another tuner card fires up to record yet another programme. It’s rare, but it happens. I think there’s some kind of race condition in the underlying Linux ivtv driver.

After living with the problem for a couple of years (which just means rebooting the machine less than once a month on average) things came to a head during our recent holiday when the MythTV box went down not once, but twice during our absence.

I had to call a friend and ask her to go over to reboot the box. On the second occasion, she couldn’t make it over until a couple of days later, so a lot of programme recordings were missed while the box was frozen.

That, for me, was the straw that broke the camel’s back. A solution had to be found, so I did some research one evening in a hotel and eventually found myself reading about the ePowerSwitch-1 Guard, manufactured by the German company, Leunig.

This is an overpriced, but pretty cool device. Basically, you plug it into the mains, network it and then plug some other device into it. At this point, you’re able to log into the ePowerSwitch via its built-in Web interface (or via a serial cable or small Windows executable) and tell it to turn off, turn on or simply restart the device that it manages.

If that was all it could do, it would already be quite a useful device, but, in my use case, I could still lose a few days of recordings if, due to travelling, it took me a few days to notice that the MythTV box had gone down and get to an Internet connection to reboot it.

Therefore, the pièce de résistance of the ePowerSwitch is its guard function. Essentially, this is a network monitor that checks the status of the device being managed and reboots it if it stops responding. Monitoring can be performed using ping, port scanning or both.

Now, if our MythTV box hangs, it will be rebooted within a minute with absolutely no involvement or intervention from me.

The device is very easy to configure and is up and running within a couple of minutes. I did have to buy a new power cord for the MythTV box, though, because the ePowerSwitch doesn’t have a normal plug socket for the device to be managed.

The only other thing I needed to do was modify a setting in the MythTV box’s BIOS, so that the machine would automatically turn itself on when power was restored after having been removed. Otherwise, the box would remain off after the ePowerSwitch cycled the power.

Leunig has other models of the ePowerSwitch that can manage four or eight devices. You can even configure master and slave set-ups. It all depends on what you need to control.

It took me a little while to find an on-line dealer prepared to sell one of these to a private individual rather than a company, but I did eventually find one and the device had already been delivered to a neighbour when we returned home from holiday.

In short, the ePowerSwitch-1 Guard does exactly what it says it does. It’s rather overpriced, but there’s nothing else quite like it on the market, thanks to its guard function. The four and eight device models are better value, but for my needs, the single device model was exactly what I needed.