[mythtv-users] Migrating RAID

Brian Wood beww at beww.org
Sat Nov 3 23:10:38 UTC 2007

Rudy Zijlstra wrote:

>>>> A lightning strike might take them both out, especially if the
>>>> cable is copper. Can you replace it with a fiber-optic link?
>>> Or just use a surge protector for the CAT5 cable on each end.
>> That's not going to work. 
>> -dsr-
> Can you explain why not? installing surge protectors i can, exchanging 
> to fiber-optic is much more difficult, as i would have to learn how to 
> make the connector on the fiber cable..... Also, i run big risk of 
> damaging a fiber cable when pulling it into place :(

Surge "protectors", especially consumer grade ones, can absorb a small
amount of energy - once.

The energy they absorb is more or less equivalent to a lightning strike
many miles away on the power line. Any closer and you and your gear are

Most do not use "self-healing" devices to absorb energy, so once they
have "protected" you they are useless. Worse, they give no indication of
their reduced status. I once saw a unit with a "protected" light that
was no more than a power indicator device. I'm not saying all such
indicators are that way, but at least some of them are.

(One reason for this is that the best self-healers are slightly
radioactive, posing problems for a consumer device. These are not
insurmountable - ionization smoke detectors use Americium 241, but it
drives costs and the "fear factor" up.)

The RJ-11 and RJ-45 jacks fond on some devices are, IMHO, marketing devices.

Believe me I know of what I speak. I worked in the B'Cast business for
many years, and real lightning "protection" is an extremely expensive
and not fully effective business. Many entire corporations are dedicated
to it, and millions of dollars are spent.

Nothing you can afford will protect you from a direct hit, or even a
near miss. Some would say that nothing will, regardless of cost. Even a
near miss can cause induced currents well beyond any "surge protector's"
capability to absorb.

For a data link breaking the current path with non-conductive material
(like glass) is probably the best way to protect the setup you describe,
but nothing's foolproof.

In any case, if you did get a direct hit, I suspect your ethernet link
would not be your highest priority, at least not immediately:-)


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