[VoiceOps] DST handling

Lee Riemer lriemer at bestline.net
Thu Nov 5 16:57:59 EST 2009

Another source of skew is multi-processor systems.  I'm not sure if it 
applies to multi-core, but I would guess it does.

Peter Beckman wrote:
> On Wed, 4 Nov 2009, Colin wrote:
>> GMT for the win.
>  Agreed, though we use UTC.  While GMT and UTC are mostly the same, 
> UTC is
>  based on atomic time and includes leap seconds that are added 
> occasionally
>  to account for the irregularity in the earth and sun's movements.  We
>  decided UTC was a more accurate and "official" representation of time.
>  GMT is based on the hypothetical average day at Greenwich, which is much
>  less scientifically accurate.
>  Everything in our system is stored as UTC, and we convert on a per-user
>  basis when displaying call logs and the like.  That way we avoid any
>  issues with DST.
>  I would make all of your CPE devices on UTC as well.  It avoids 
> confusion
>  about what time zone any date/time in your system is on the back end.
>  Build the conversion into your front-end systems and reporting on a
>  per-customer basis.
>  You also avoid calls that were really 4 minutes, but get billed as -56
>  minutes or 64 minutes for calls during the change from/to DST.
>  In discussing time, one of my providers avoids syncing their servers to
>  the correct time on an ongoing basis (i.e. with ntpd), with the argument
>  that if they sync during calls, billing would be wrong.  Some of there
>  servers therefore skew a LOT, and sometimes their call servers can be 
> off
>  the real time by _HOURS_ (I suspect this is due to running Asterisk 
> on VMs
>  which are notoriously bad at keeping time).  I've griped about it, but
>  they say they only sync the time when there are no calls at midnight,
>  which never happens.
>  Has anyone else been frustrated by the lack of punctuality/analness when
>  it comes to making sure clocks are accurate when it comes to call 
> records?
> Beckman
> --------------------------------------------------------------------------- 
> Peter Beckman                                                  
> Internet Guy
> beckman at angryox.com                                 
> http://www.angryox.com/
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