This weekend there was a solar CME warning that finally had no perceptible impact. However, I was wondering what could be done to mitigate the effects in case a large one took place. Are there any devices available in the market to protect servers from the pernicious electromagnetic effects (or help paliate them in some way)? (Like for example, an special power source or cage)

I'm not thinking on protecting a large server farm, but perhaps one or two critical machines.

Actually there are RF/EMI shielded racks on the market, what I don't know is if they could withstand a solar flare. Also, critical server rooms can be built as a Faraday cage as one of the answers pointed. It would be interesting to know the percentage of server rooms that are built with this in mind.


Certainly having your equipment on surge-protected power supplies, ideally UPSs, makes some sense for this scenario but the only way to add significant EM protection would be by placing your hardware inside a well grounded Faraday cage of some sort. I'm not aware of any commercially available products in this area and obviously the size of installation would be key to the resources needed to carry out this work but I do know that given the time and money it would be possible to build an entire data centre inside an effective Faraday cage if you so desired.

  • Fascinating topic. Wouldn't the EM event make its way into the Faraday cage via the conductors going in and out? While the data connectivity could be fiber, it could still be carried on the power lines... – Tevo D Jan 23 '12 at 13:29
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    "Into/conductors going in and out" - odd way of putting it but no, that said the whole concept of 'Earth' is a variable one, and if the EM was strong enough then certainly it could affect the earth levels somewhat but then that would still be common to all local devices so the impact would be limited and also if it were that bad, well there's be no users to complain because we'd all be dead - as for the power lines I mentioned using surge-protection and/or UPSs which would deal with that issue. – Chopper3 Jan 23 '12 at 13:46
  • I grant that I am no scientist, but it is my understanding that an EM event would contain a surge across a wide part of the EM spectrum, and as such, the conductors penetrating the cage would be susceptible to pick up as well as re-radiate this energy, particularly at higher RF frequencies. Probably not something a typical UPS would be able to filter or prevent? – Tevo D Jan 23 '12 at 13:56
  • @TevoD: No, but if the UPS is close enough to the faraday cage (either inside or outside) then the conductors (antenna's) will be too short to effectively radiate. – MSalters Jan 23 '12 at 14:04

The surge generated by a solar event is generally caused by swift oscillations in Earth's magnetic field which in turn induces current in long conductors. In extreme cases (I think that 1980's era X-class solar flare that blacked out a lot of Canada was one) the magnetic fields from the CME itself reach the ground for big-big fun; we haven't yet had a flare that size in the Internet era.

This means there are two surges you have to defend against:

  1. The indirect-effect surge coming down your mains feed thanks to those long transmission lines acting as antenna for the magnetic fields.
  2. The direct-effect induced current in your own electrical plant.

The first type can be handled by Ye Olde Surge Suppressors, or if you want to get fancy with it a line conditioner will do the job better.

The second type is a lot harder to defend against. Happily, you're not likely to be vulnerable to it since it requires long, straight runs of conductor. Long twisted-pair runs may get higher incidents of bad signals on the wire but shouldn't induce enough voltage to smoke equipment. Long power runs may pick up dirtier power than normal, so equipment sensitive to such small voltage changes may act badly.

A Farraday Cage does offer some protection, so long as it doesn't share a ground with the powered equipment inside.

  • So it is not a good idea to ground the Faraday cage to a regular AC socket ground contact. – Mister Smith Jan 25 '12 at 8:34

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