unruh wrote:
On 2010-08-16, ask <[email protected]> wrote:
On Aug 2, 1:35?am, konsu <[email protected]> wrote:
Hello list,
I work for an investment bank with 300 UNIX servers, around 3000
workstation PCs and would like to ask some questions to more
experience users.
a) Are there any banks relying on ntp pool project or should we
consider having our own GPS clock ?
If you have any sort of legal and practical requirement for keeping
accurate and tracable time you need your own "stratum 1" source.
I'd get a GPS timeserver for each physical location (unless you trust
your internal network very much) and then on each server and
workstation, as others suggested, you configure to use your various
GPS-based ntp servers.
Meinberg donated a couple of GPS NTP time server to the NTP Pool
project and their accuracy, stability and ease of use are just
incredible. The time quality is so good that ntpd even far away
(network wise) usually pick them despite having more nearby other
"good" time sources.
The problem is not with the sources. The problem is with the computer
crystals and changes in temp. Because ntp is so so slow in converging,
changes in temp show up at the usec level. Ie, it is easy using even
just a GPS18 to get 10usec accuracy. At the 1us level ntp has troubles.
(Since I believe most of the readin ability of ntp is at the 1us level,
that is probably the goal)
- ask
--
http://askask.com/
If you require accuracy at the microsecond level, put your equipment in
a controlled environment! If the temperature in the room where the
equipment resides is an unvarying 68 degrees F or 20 degrees C you will
get a better and more stable time. This may not be easy to do but it's
essential for the very best time. Actually just about any temperature
that will not damage the hardware will work equally well as long as it
does not vary minute to minute or hour to hour.
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