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Fri Sep 7 14:54:47 2001 UTC (22 years, 11 months ago) by
harris41
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1: <HTML>
2: <HEAD>
3: <TITLE>LON-CAPA Time Synchronization</TITLE>
4: </HEAD>
5: <BODY>
6: <H1>LON-CAPA Time Synchronization</H1>
7: <P>
8: Scott Harrison
9: </P>
10: <P>
11: Last updated: 02/07/2001
12: </P>
13: <P>
14: This file describes issues associated with LON-CAPA
15: and time synchronization.
16: </P>
17: <H3>Importance</H3>
18: <P>
19: Since LON-CAPA machines are involved with
20: the submission of homework, quizzes, and
21: exams to the instructor, it is important that
22: the time of the server be kept accurately and precisely.
23: </P>
24: <P>
25: Accuracy involves
26: </P>
27: <pre>
28: I will explain the components of ntp and how they
29: interrelate on a LON-CAPA system
30:
31: There are three relevant components here:
32: 1. a correct /etc/ntp/step-tickers,
33: 2. a correct /etc/ntp.conf
34: 3. enabling xntpd for boot up
35:
36: Without /etc/ntp.conf, /etc/rc.d/init.d/xntpd won't do anything.
37: With /etc/ntp.conf but without /etc/ntp/step-tickers, Gerd is correct
38: when he says:
39:
40: > What I do know is that if the clock in the CMOS is off by too much,the normal
41: > ntp will not work. Instead, the clock has to be forced to synch initially,and
42: > from then on can be automatically adjusted.
43:
44: The unix commands for Gerd's manual approach are:
45: /etc/rc.d/init.d/xntpd stop
46: /usr/sbin/ntpdate ntp.msu.edu (or whatever your ntp server is)
47: /etc/rc.d/init.d/xntpd start
48:
49: To force xntpd to avoid the offset problem, defining
50: /etc/ntp/step-tickers does the trick.
51:
52: With /etc/ntp.conf and /etc/ntp/step-tickers, xntp still may not
53: work (depending on whether the last instruction was followed
54: for the LON-CAPA installation, see
55: http://install.lon-capa.org/docs/3.1/instructions_with_cd.html)
56:
57: Making sure xntp starts up upon boot time should simply
58: be a matter of:
59:
60: /sbin/chkconfig xntpd on
61:
62: Finally, the correct settings for /etc/ntp.conf
63: and /etc/ntp/step-tickers are:
64:
65: 1 line with the ip address of your ntp server
66:
67: For instance:
68:
69: echo "whistler.sfu.ca" > /etc/ntp/step-tickers
70: echo "whistler.sfu.ca" > /etc/ntp.conf
71:
72: Everyone is currently setting these and other LON-CAPA conf
73: files manually after cvs upgrades, because
74: there were several parties who were
75:
76: * doing different things
77: * in different ways
78: * for different reasons
79: * for different institutions
80: * for their machine-specific configurations
81:
82: I was not able to make everyone happy with
83: "make configinstall". For the future, we (Guy and I) do think
84: we've come up with a new way to do everything
85: for everyone for updating configuration files
86: as the CVS source repository changes.
87:
88: -Scott
89: </pre>
90: </body>
91: </html>
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