[ntp:questions] Selective peerstats collection

David Taylor david-taylor at blueyonder.co.uk.invalid
Sat Dec 8 16:59:28 UTC 2012


On 08/12/2012 10:25, Hal Murray wrote:
> In article <k9uqvn$mf2$1 at dont-email.me>,
>   David Taylor <david-taylor at blueyonder.co.uk.invalid> writes:
>
>> The problem is that if it takes, say, 3 months to wear out the SD card,
>> I don't really have that long to wait!  My time costs a lot more than
>> the SD card.  Likely I will turn off statistics collection outside major
>> NTP changes.
>
> I think it will last years.  I can't prove that.  I might be wrong.
>
> I don't know how to evaluate your time.  A low cost SD card is ballpark
> of $10.  If your time is worth anything, you have already spent more
> than that discussing this.  :)
>
> Just logging to the SD card is simple and doesn't waste time trying to
> figure out how to do something else.
>
> If it dies after 3 months, you go "Oh shit" and put the system back
> together.  I'm assuming you backup the log files over to another
> system occasionally, say once a day.  So if the SD disk dies, you
> lose at most a day of log files.
>
> Then you get to decide if swapping in a new SD card every now and then
> is cheaper than working out the alternatives.
>
> ----------
>
>
> I have a small embedded type box generating lots of log files.  It's
> on a UPS.  I'd like to minimize the power it burns to maximize the time
> it can run on the UPS.  Several years ago, I put all the log files
> into ramdisk so the disk could spin down and occasionally copied them
> to the real disk.
>
> After I got that stuff all debugged, I discovered that it didn't save
> enough power to be worth the effort.  So I ripped out that stuff and
> went back to just logging to disk.

I suppose I'm prepared to put the time in to understanding the issues 
involved, but not into getting half a dozen different brand of SD cards 
and seeing when they fail.  Yes, having a 4 GB or 8 GB SD card which can 
be loaded from the most recent backup of the working SD card would be 
more than adequate in this particular case.  As it happens, the log 
files are backed up daily with a scheduled task on the Windows PC and 
PKZip25 (yes, that old) accessing the data through a Samba share.  Even 
then, I'm interested to know "how well does NTP work", and that should 
be normally constant.  Retaining the log files is in no way critical.

However, what I would like to know is the answer to: "What is causing 
the most write activity on the SD card, what effect does that have on 
its life, and how can such activity be minimised?"  But if I don't find 
that out it doesn't really matter.

Thanks for the information on your own system.  The nice thing about 
this NTP server is that it takes less than 4 watts ... so I'm definitely 
/not/ worrying about power consumption!  <G>

(But people are telling me that that are employing these devices 
remotely, e.g. on mountain tops, solar powered perhaps, so if they are 
going to fail after just a few weeks or months it would be helpful to be 
warned in advance.)
-- 
Cheers,
David
Web: http://www.satsignal.eu



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