[rrd-users] Re: rrd graph x-axis shift caused by --step

[Stefan Finzel]

Thank you Alex,
you are right. It looks like I've to wrap rrdtool to set a temporary TZ.

Summertime is no problem, as a raw calendaric view is required.

Nethertheless i am still confused that only by changing --step ### the 
graph looks different.

Stefan


Alex van den Bogaerdt schrieb:
> On Fri, Jun 16, 2006 at 12:50:55PM +0200, Stefan Finzel wrote:
>
>   
>> drawing one datapoint per day is shifting my graphs x axis by two hours 
>> (correlated to my local time zone CEST?) using --step 86400 by rrdtool 
>> create. There is no shift using --step 3600. Something obvious was 
>> missed here?
>>     
>
>   
>> Data are created using the midnight timestamps of the local zone
>>     
>
> Data is input using the local time zone but is immediately
> normalized to fit in {n*86400} second time steps.  This comes
> down to fit in UTC time.
>
> If you say "--step 86400" you are asking rrdtool to have time slots
> running from { (n-1)*86400 } to { n*86400 }.
>
>   
>> Dependent of the setting of --step the x-axis is /not shifted. Using 
>> --step 3600 will enlarge my rrd files to keep the same time period, 
>> won't it?
>>     
>
> You have 24 times the amount of rates in your file so yes, your file
> will be bigger.  It will be slightly less than 2400% of the file size
> you get with step 86400.
>
>   
>> I am not able/allowed to modify the environement variable TZ as it's 
>> setting is already used and required by the script.
>>     
>
> You can have a separate TZ for rrdtool, just as I show here for date:
>
> $ date;TZ="" date
> Fri Jun 16 13:07:03 CEST 2006
> Fri Jun 16 11:07:03 UTC 2006
>
> and also:
>
> $ TZ="" date;date
> Fri Jun 16 13:07:03 CEST 2006
> Fri Jun 16 11:07:03 UTC 2006
>
> As you can see, this TZ is only for one command 
>
> On unix and alike:
>
> TZ="" rrdtool ...whatever...
>
> on dos and alike you may need to call another script that
> sets a new time zone: in stead of calling rrdtool directly,
> call rrd_tz.bat and let this script set a new time zone before
> it calls the real rrdtool
>
>
> But what about summertime ?
>
>   

-- 
_________________________________________________________
        Stefan G. R. Finzel, Dipl. Phys. (Univ.)
  Ochsenkopfstr. 5, D-95478 Kemnath, +49 (0)9642 704448



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