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Re: Strange dates with ntpd
On 08/30/12 08:58, Julian Coleman wrote:
This is already a strange date to start with. It should be check why we
get a date this far of
after start-up - does the machine have a reasonably working real time
Has anyone else seen ntpd not set the time correctly? For example:
Sat Apr 19 20:03:55 BST 10859
ntpd will is supposed to be designed to work at any time even though it
uses 32-bit second
time stamps. 2^32 seconds are roughly 136 years. The NTP time stamp
(based in seconds since Jan 1st 1900) will
wrap on 06:28:16 UTC on 7 Feb 2036 (Wikipedia). Ntpd will work if and
only if the current time
is within +-68 year of our 'official' time, The starting point you cited
is a bit in the future and
ntpd locked onto that era of 136 year cycles.
Now rdate just transfers just the unix seconds value (also 32-bit). On
03:14:08 UTC on 19 January 2038
rdate will run into the wrap of its time stamp.
So to sum up. ntpd thinks is is right (but far in the wrong era of 136
year cycles). rdate currently works,
as is blindly transfers to corrects unix utc value.
The 640 ms difference you saw is the sub second difference (rdate has
only second resolution).
The fix usually is to make sure that the current system time is within
+- 68 years of the 'official' time.
So there is nothing wrong with ntpd, but the start value was not
when the peerings look OK:
remote refid st t when poll reach delay offset jitter
+stratum-2-core- 220.127.116.11 2 u 58 64 377 134.192 -2.756 0.121
*ntppub.le.ac.uk 18.104.22.168 2 u 28 64 377 27.818 -3.635 1.175
-anor.coris.org. 22.214.171.124 3 u 16 64 377 0.316 -19.739 0.221
+orthanc.coris.o 126.96.36.199 3 u 6 64 377 0.365 -3.968 0.074
This is a sparc64 running 6.99.10. I'd replaced the system board, so the
clock almost certainly contained the wrong time. At startup, it ran ntpdate
before ntpd. /var/log/messages contains:
Apr 19 10:52:22 orion -: 10859-04-19T10:52:31.361110+01:00
orion.coris.org.uk ntpdate 181 - - step time server 188.8.131.52 offset
I ran `rdate<remote>` while ntpq was still running, the time was set to
2012, and ntpd continued to run (it showed a jump in the offset (to 640ms)
and jitter for all the peers).
PS. Real date was approximately Aug 30 07:26 BST at this point.
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