Time synchronization on the CTIO computers is done as follows:
an automatic job is invoked on Cerro Tololo machine ctioa7 at
0045h, 0445h, 0845h, 1245h, 1645h, 2045h.
this job runs the 'ntpdate' program which uses the ntp protocol
to acquire
precise time and other information from each of the following sites:
- norad.arc.nasa.gov
- tick.usno.navy.mil
- tock.usno.navy.mil
- ntp1.sura.net
- ntp2.sura.net
- louie.udel.edu
- ntp.css.gov
the ntpdate program uses the data provided by the
above machines and
applies some sophisticated corrections to the data to compensate for
packet transmission time, and sets the time on ctioa7 accordingly.
all other SunOS, Solaris, and Linux computers run an
automatic job
once an hour on the hour.
this job is 'rdate' which synchronizes their
time w/ ctioa7 (for machines
on Cerro Tololo) or w/ ctios5 (for machines in La Serena).
Here is the crontab entry as it appears on ctioa7:
45 0,4,8,12,16,20 * * * /usr/etc/ntpdate -s -p 8 norad.arc.nasa.gov \
tick.usno.navy.mil tock.usno.navy.mil ntp1.sura.net ntp2.sura.net \
louie.udel.edu ntp.css.govra7(42)
Here is the typical SunOS crontab entry on Cerro Tololo:
0 * * * * /bin/touch /dev/console;/usr/ucb/rdate ctioa7 \
1> /dev/null 2> /dev/null
Jim Hughes (jhughes@noao.edu)