In <[EMAIL PROTECTED]> J Robinson <[EMAIL PROTECTED]> writes: > */12 * * * * /usr/sbin/ntpdate -s timeserver1 > timeserver2 timeserver3 timeserver4
By default, ntpdate sends 4 packets to each ntp server to try and get somewhat accurate time. So, on average, you are sending one packet every 3 minutes to each of those servers. That isn't horrible, but it isn't very good either. Another problem with running ntp via cron like that is that you will send all your packets on the minute. When lots of people do this, it means that there is a spike in usage every minute as all the packets from these cron jobs come in at exactly the same time. This increases the load and reduces the accuracy of the time you are getting. > I (probably mistakenly) assumed that running ntpdate > periodically would put less load on my servers than > using ntpd, and I also assumed that it wouldn't put > undue load on the ntp servers either. Is these > assumptions wrong? Yes, your assumption is wrong. When running well, ntpd will send one request every 1024 seconds, about once every 15 minutes. So, what you are doing is generating about 5 times as much load as just using ntpd. Worse, ntpd will do a *much* better job of keeping your clock in sync with the correct time. The ntpdate command can make the clock jump forward or backwards if the offset is too large, which can sometimes cause programs to do funny things. Video and music may skip or hang for short periods, timestamps on files can get set wrong and might not be backed up, etc. Using ntpd, your clock will run more smoothly. -wayne _______________________________________________ timekeepers mailing list [email protected] https://fortytwo.ch/mailman/cgi-bin/listinfo/timekeepers
