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howtos:network_services:ntp [2013/03/01 13:49 (UTC)] – Added an introduction + some explanations + edited some sections kikinovak | howtos:network_services:ntp [2014/02/17 06:35 (UTC)] – kikinovak | ||
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===== Introduction ===== | ===== Introduction ===== | ||
- | When several users manipulate shared data on different client PCs on a network, it's important that these machines are all synchronized. Unfortunately, | + | When several users manipulate shared data on different client PCs on a network, it's important that these machines are all synchronized. This is especially true if you share files over NFS, or if you use NIS for centralized authentication. You'll get all sorts of weird errors if your clocks are out of sync. Unfortunately, |
That's where NTP (//Network Time Protocol//) comes in handy. It allows networked machines to adjust their clocks so as to be perfectly synchronized. A series of public time servers on the Internet allow the reception of the exact time. From this point, we can use NTP in several ways. | That's where NTP (//Network Time Protocol//) comes in handy. It allows networked machines to adjust their clocks so as to be perfectly synchronized. A series of public time servers on the Internet allow the reception of the exact time. From this point, we can use NTP in several ways. | ||
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<note tip> | <note tip> | ||
+ | | ||
+ | ===== Monitor the performance of ntpd ===== | ||
- | === Synchronizing at boot time === | + | You will notice that the logfile ''/ |
- | If instead of using a daemon, all you want to do is to synchronize time once per boot, it is possible to add the command | + | < |
- | + | statsdir / | |
- | ~# cat /etc/rc.d/rc.local | + | statistics loopstats |
- | #!/bin/sh | + | filegen loopstats file loops type day link enable |
- | # | + | </ |
- | # /etc/rc.d/rc.local: | + | |
- | # | + | You have to create |
- | # Put any local startup commands in here. Also, if you have | + | < |
- | # anything that needs to be run at shutdown | + | 56690 3950.569 0.001199636 2.297 0.001830770 0.571576 10 |
- | # make an /etc/rc.d/rc.local_shutdown script and put those | + | </ |
- | # commands in there. | + | |
- | | + | The first and second number are the UTC time (expressed as [[http://en.wikipedia.org/wiki/ |
- | | + | |
- | | + | To monitor the performance of '' |
- | ntpd -qg & | + | |
+ | < | ||
+ | $ awk ' | ||
+ | $ awk ' | ||
+ | $ gnuplot | ||
+ | gnuplot> set xzeroaxis | ||
+ | gnuplot> plot 'time' with yerror | ||
+ | gnuplot> plot ' | ||
+ | </code> | ||
+ | |||
+ | Given enough data, visual examination of the plots will allow you to see peculiarities in '' | ||
====== Sources ====== | ====== Sources ====== | ||
* Originally written by [[wiki: | * Originally written by [[wiki: | ||
+ | * Performance monitoring section contributed by Dominik Drobek | ||
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