Re: [R] Simulations in R during power failure

From: Ted Harding <Ted.Harding_at_nessie.mcc.ac.uk>
Date: Sun 27 Aug 2006 - 17:31:50 EST


On 27-Aug-06 mel wrote:

> bbvaughn@bellsouth.net a écrit :
> 

>> Hi everyone,
>> I recently ran a simulation on a computer using R that was hooked up
>> to a UPS. There was one time when the power was out for length and
>> the computer shut down. I was worried that I had lost the simulation,
>> but upon booting the machine up, I heard the processor kick in.

I'm not sure what you meant by "heard the processor kick in"! If you really were rebooting, then everything would start from scratch anyway.

Most UPS's can be connected with a cable -- serial or network -- to the computer so as to cause the computer to shut-down cleanly, or execute some other procedure, once the UPS has been standing-in for the mains for a certain length of time and is about to shut itself down.

So one things that may have happened is that when all programs were cleanly shut down in this way, R (if configured to automatically save its state when being closed down in ".Rdata" etc -- see comment about save.image() below and also see "?quit") would have been in a position to resume when re-started.

Another possibility (depending on UPS and hardware configuration) is that when the mains power had been off for a certain length of time the UPS communicated with the computer to put it into "stand-by", with the current state being swapped out to disk; the computer would then draw minimum power from the UPS, which in turn would be able to remain active for a much longer duration. Then, when power came back on, the UPS would tell the computer to "resume". However, I doubt this would be able to cope with a power outage of several days such as might ensue from a hurricane!

However, all this is just guesses. You need to find out what has been configured for that comnputer and UPS.

In any case, whenever there is a serious risk of power interruptions, Mel's advice below is the way to go! Though simply writing tables to disk my not be sufficient. If you really want to be able to resume where you left off, then use the function save.image() whose options and description can be found under "?save".

>> It sounded like the simulation had resumed.
>> Does anyone have any experience with this? Because I live in Florida
>> and there is a possibility of another hurricane. And I am running a
>> huge simulation which may or may not finish before this hurricane
>> finishes.
>> What options are there in saving a simulation and it picking up where
>> it left off?
>> Thanks,
>> Brandon

> 
> write your results, let's say every hour or 30' on your disk.
> something like
> if (substr(date(),...)=='30') write.table(...)
> where it could take place
> 
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Date: 27-Aug-06                                       Time: 08:31:44
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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Sun Aug 27 17:38:38 2006

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