This is the NTP home page that some people like to see here
8. TroubleshootingIf you have set up your software, you usually want to know ntpd commands whether it works. This section discusses topics related to configuration, monitoring, troubleshooting, and debugging of ntp offset units xntp.
8.1. MonitoringWithout any doubt, troubleshooting requires monitoring. Somehow you must find
What Is Ntp Offset
out that something is wrong before you wonder how to fix it.
8.1.1. If I think my NTP server is working fine, what could I do to confirm this?8.1.2. How do I use
Ntp Offset Too Large
peerstats and loopstats?8.1.3. How can I see the Time Difference between Client and Server?8.1.4. What does 257 mean as value for reach?8.1.5. What can I use these statistics files for?8.1.1. If I think my NTP server is working fine, what could I do to confirm this?
One of the quickest commands to verify ntp offset meaning that ntpd is still up and running as desired is ntpq -p. That command will show all peers used and configured together with their corner performance data.As the above command requires periodic invocation to monitor the performance, it is also recommended to enable statistic files in ntpd. See also Q: 8.1.2. and Q: 8.1.3..
8.1.2. How do I use peerstats and loopstats? I use the following lines in /etc/ntp.conf to enable loopfilter statistics (See the line starting with statistics). New files are created every day, and the current files are available as /var/log/ntp/peers and /var/log/ntp/loops. Older files are archived as /var/log/ntp/peers.YYYYMMDD and /var/log/ntp/loops.YYYYMMDD:statistics loopstats statsdir /var/log/ntp/ filegen peerstats file peers type day link enable filegen loopstats file loops type day link enableUsually I only monitor the loops file. Table 3 lists the individual fields of each file. I'll show examples for peerstats and loopstats for version 3 and 4 in the following screens.Table 3. Statistic FilesFile TypeVersionList of Fieldsloopstats3day, second, offset, drift compensation, polling interval4day, second, offset, drift compensation, estimated error, st
-s statsdir ] [ -t key ] [ -v variable ] [ -V ntp jitter variable ] [ -x ] Description The ntpd program is an operating system daemon which sets and maintains the system ntp linux time of day in synchronism with Internet standard time servers. It is a complete implementation of the Network Time Protocol (NTP) version 4, but also retains compatibility with version 3, as defined by http://www.ntp.org/ntpfaq/NTP-s-trouble.htm RFC-1305, and version 1 and 2, as defined by RFC-1059 and RFC-1119, respectively. ntpd does most computations in 64-bit floating point arithmetic and does relatively clumsy 64-bit fixed point operations only when necessary to preserve the ultimate precision, about 232 picoseconds. While the ultimate precision, is not achievable with ordinary workstations and networks of today, it may be required with future gigahertz CPU clocks and gigabit LANs. http://doc.ntp.org/4.1.0/ntpd.htm How NTP Operates The ntpd program operates by exchanging messages with one or more configured servers at designated poll intervals. When started, whether for the first or subsequent times, the program requires several exahanges from the majority of these servers so the signal processing and mitigation algorithms can accumulate and groom the data and set the clock. In order to protect the network from bursts, the initial poll interval for each server is delayed an interval randomized over 0-16s. At the default initial poll interval of 64s, several minutes can elapse before the clock is set. The initial delay to set the clock can be reduced using the iburst keyword with the server configuration command, as described on the Configuration Options page. Most operating systems and hardware of today incorporate a time-of-year (TOY) chip to maintain the time during periods when the power is off. When the machine is booted, the chip is used to initialize the operating system time. After the machine has synchronized to a NTP server, the operating system corrects the chip from time to time. In case there is no TOY chip or for some reason its time is more than 1000s from the se
working Issues related to software problems. Post Reply http://www.centos.org/forums/viewtopic.php?t=20630 Print view Search Advanced search 8 posts • Page 1 of 1 jonaskellens Posts: 45 Joined: 2009/03/20 16:33:09 Location: Ghent, Belgium NTP synchronisation not working Quote Postby jonaskellens » 2009/10/29 11:09:48 I'm getting the following errors :bash-3.2# /usr/sbin/ntptimentp_gettime() returns code 5 (ERROR) time ce93f52c.a1922000 Thu, ntp offset Oct 29 2009 12:04:12.631, (.631136), maximum error 16384000 us, estimated error 16384000 usntp_adjtime() returns code 5 (ERROR) modes 0x0 (), offset -1331.000 us, frequency -19.457 ppm, interval 1 s, maximum error 16384000 us, estimated error 16384000 us, status 0x41 (PLL,UNSYNC), time constant 6, precision ntp time error 1.000 us, tolerance 512 ppm,bash-3.2# /usr/sbin/ntpdate29 Oct 12:04:15 ntpdate[15911]: no servers can be used, exitingMy /etc/ntp.conf :# Permit time synchronization with our time source, but do not# permit the source to query or modify the service on this system.#restrict default kod nomodify notrap nopeer noqueryrestrict default kod nomodify notrap nopeerrestrict -6 default kod nomodify notrap nopeer noquery# Permit all access over the loopback interface. This could# be tightened as well, but to do so would effect some of# the administrative functions.restrict 127.0.0.1 restrict -6 ::1# Hosts on local network are less restricted.#restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap# Use public servers from the pool.ntp.org project.# Please consider joining the pool (http://www.pool.ntp.org/join.html).server 0.centos.pool.ntp.orgserver 1.centos.pool.ntp.orgserver 2.centos.pool.ntp.org#broadcast 192.168.1.255 key 42 # broadcast server#broadcastclient # broadcast client#broadcast 224.0.1.1 key 42 # multicast server#multicastclient 224.0.1.1 # multicast clie
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