[mythtv-users] Migrating RAID

[Joris Dobbelsteen]

Where I live, there was a direct hit of lighting on a tree. I think it
was 15 meters away from the house I live in. The end-result was that the
tree had to be cut down. After that the trunk was sliced with a
chainsaw. These pieces fell into 5 parts. Effectively, the lightning
sliced the tree in 5 parts. You really believe sensative electrical
equipment is going to survive such forces (even with surge protectors)?

In our case a electrical cable was running a few meters from the tree,
which also got it and resulted in a lot of damage to computer equipment.
That said, I should note that they where connected in every possible
way: power, network and telephone line. Some systems didn't function
afterwards, but there are also a few that worked well until they got
replaced due to old age. Perhaps a few imtermediate fuses and lots of
attached equipment to the power line mitigated the effects a bit.

That said, what is the risk of a lightning strike hitting you: its
extremely low. And if it happens the usual result is usually complete
destruction.

If you are posting this on the mythtv-users list, you are not going to
say that the data has a very high importance? Alternatively you can make
backups of your important data (which you should, since RAID won't
protect against user error or higher-level data corruption) to something
like a DVD.
I live comfortably making automated backups to a secondary system in the
same building. In fact, I'm running a bit behind with archiving it to a
DVD (and I didn't think I have put the most important data on DVD, in
fact).

- Joris

>-----Original Message-----
>From: mythtv-users-bounces at mythtv.org 
>[mailto:mythtv-users-bounces at mythtv.org] On Behalf Of Brian Wood
>Sent: zondag 4 november 2007 1:31
>To: Discussion about mythtv
>Subject: Re: [mythtv-users] Migrating RAID
>
>Rudy Zijlstra wrote:
>> Dan Ritter wrote:
>>> On Sat, Nov 03, 2007 at 05:10:38PM -0600, Brian Wood wrote:
>>>   
>>>> 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 
>>>>> :(
>>>>>       
>>> Brian gave a good explanation.
>>>
>>> You can buy premade fiber cables of varying lengths.  100 
>meters even 
>>> is not unusual.
>>>
>>> You'll want to run it through a conduit of some sort, but -- aren't 
>>> you running the copper through a conduit now? Otherwise I would 
>>> assume that you will be replacing it several times a year
>>> -- lawn mowing, for instance.
>>>
>>> -dsr-
>>>   
>> It is running though a conduit.. which is pretty full. Which means i 
>> have no space for the connector to pull through :( Also, 
>inside i have 
>> to go through some small spaces, and increasing space for this is a 
>> major work :(  Cat 5e cable can stand quit a bit off pulling, and 
>> sharp corners. Not so certain on fiber optic cable in that respect.
>> 
>> hmmm, could do it for a short run, simply to have the isolation. Do 
>> not care too much about a device being fried. Problem with an almost 
>> direct hit is, i am rather afraid it would not only fry the switches 
>> at both ends of that cable, but might actually continue on through 
>> those switches onto the rest of the network.
>> 
>
>As I said, in the event of a direct hit your network will be 
>the least of your problems, you likely wouldn't have any 
>computers left to use it.
>
>Nothing can help such a disaster, and I'd worry more about 
>your house burning down.
>
>There are optical isolators available, to break the copper 
>continuity, but I really don't think it's worth it in your 
>situation. You could even microwave the signal of the distance 
>is short. There are industrial T1 RF hops available, but 
>expensive. I'm sure you ae aware of the limitations of 
>802.11(x), but it does have its uses.
>
>If you are really really concerned about data loss, an 
>off-site B/U in another state or continent is always good. 
>Burning to optical media then moving the disks off site works as well.
>
>The equation is simple: Figure out what it would cost to 
>replace your data, and don't spend more than that "protecting" it.
>
>beww
>
>
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