[ntp:questions] Massive Jitter & Drift Preventing Syncronization?

Dan Check dan at jloreview.com
Mon Dec 19 20:14:10 UTC 2005


Hi,

I'm running into terrible system clock problems with a Sun Fire X2100  
running a Debian etch kernel (2.6.12-1-amd64-k8-smp #1 SMP Wed Sep 28  
02:57:49 CEST 2005 x86_64 GNU/Linux).  The system clock falls out of  
sync really aggressively -- at a rate of a couple of minutes every  
hour.  Any help on this would be hugely appreciated.

NTP doesn't work at all unless I add the burst and iburst options to  
the servers, and then it seems to sync periodically,  but it doesn't  
do the gentle time correction that I've come to know and love from  
ntp.  Is this because my system clock is naturally too far out to  
lunch?  Is there a different way that I can get it to a baseline of  
acceptable performance, and would that help NTP to do its job?

I've currently got ntp requests going out over both eth1 and eth0,  
onto the internet and onto a local subnet, so I don't think network  
problems are a root cause here.

Here's some ntpq output (notice the massive jitter):

cairo:~# ntpq -p
      remote           refid      st t when poll reach   delay    
offset  jitter
======================================================================== 
======
eddie.psaux.com 69.25.96.13      2 u   41   64  377  126.531  -178278  
1469.35
snm.sd.dreamhos 164.67.62.194    2 u    1   64  377   76.850  -174947  
5826.25
dns.ziandra.net 192.43.244.18    2 u    1   64  377  146.722  -187680  
9415.62
69.38.165.70    .STEP.          16 u    - 1024    0    0.000    0.000  
4000.00
69.38.165.70    17.254.0.27      3 u    2   64  377   32.126  -174999  
8972.49
cudns.cit.corne 192.43.244.18    2 u    2   64  377   68.414  -188343  
9871.54
hickory.cc.colu 18.145.0.30      2 u    2   64  377   15.159  -176542  
7009.97
192.168.1.202   216.165.129.244  2 u    1   64  377    0.089  -176454  
7924.23

And here are the logs... notice the frequent large syncs...  And it  
gives me a "kernel time sync disabled" but never says "kernel time  
sync enabled" after that, which is the behavior that I'm used to...

Dec 19 14:28:41 cairo ntpd[24714]: ntpd 4.2.0a at 1:4.2.0a+stable-2-r  
Fri Feb  4 19:20:53 CET 2005 (1)
Dec 19 14:28:41 cairo ntpd[24714]: precision = 1.000 usec
Dec 19 14:28:41 cairo ntpd[24714]: Listening on interface wildcard,  
0.0.0.0#123
Dec 19 14:28:41 cairo ntpd[24714]: Listening on interface  
wildcard, ::#123
Dec 19 14:28:41 cairo ntpd[24714]: Listening on interface lo, XXXXXX#123
Dec 19 14:28:41 cairo ntpd[24714]: Listening on interface eth0,  
XXXXXXXX#123
Dec 19 14:28:41 cairo ntpd[24714]: Listening on interface eth1,  
XXXXXXXX#123
Dec 19 14:28:41 cairo ntpd[24714]: kernel time sync status 0040
Dec 19 14:28:41 cairo ntpd[24714]: frequency initialized 0.000 PPM  
from /var/lib/ntp/ntp.drift
Dec 19 14:29:19 cairo ntpd[24714]: synchronized to 66.33.216.11,  
stratum 2
Dec 19 14:29:19 cairo ntpd[24714]: time reset -53.294103 s
Dec 19 14:29:19 cairo ntpd[24714]: kernel time sync disabled 0041
Dec 19 14:32:46 cairo ntpd[24714]: synchronized to 69.38.165.70,  
stratum 3
Dec 19 14:33:37 cairo ntpd[24714]: synchronized to 128.59.59.177,  
stratum 2
Dec 19 14:33:39 cairo ntpd[24714]: no servers reachable
Dec 19 14:33:50 cairo ntpd[24714]: synchronized to 69.38.165.70,  
stratum 3
Dec 19 14:33:52 cairo ntpd[24714]: synchronized to 128.59.59.177,  
stratum 2
Dec 19 14:34:42 cairo ntpd[24714]: synchronized to 69.38.165.70,  
stratum 3
Dec 19 14:34:42 cairo ntpd[24714]: synchronized to 66.92.250.40,  
stratum 2
Dec 19 14:34:44 cairo ntpd[24714]: no servers reachable
Dec 19 14:34:57 cairo ntpd[24714]: synchronized to 66.92.250.40,  
stratum 2
Dec 19 14:35:47 cairo ntpd[24714]: synchronized to 66.33.216.11,  
stratum 2
Dec 19 14:35:52 cairo ntpd[24714]: no servers reachable
Dec 19 14:37:17 cairo ntpd[24714]: synchronized to 66.33.216.11,  
stratum 2
Dec 19 14:38:07 cairo ntpd[24714]: no servers reachable
Dec 19 14:40:27 cairo ntpd[24714]: synchronized to 132.236.56.250,  
stratum 2
Dec 19 14:41:16 cairo ntpd[24714]: synchronized to 66.33.216.11,  
stratum 2
Dec 19 14:41:21 cairo ntpd[24714]: no servers reachable
Dec 19 14:41:30 cairo ntpd[24714]: synchronized to 132.236.56.250,  
stratum 2
Dec 19 14:42:24 cairo ntpd[24714]: no servers reachable
Dec 19 14:42:43 cairo ntpd[24714]: synchronized to 128.59.59.177,  
stratum 2
Dec 19 14:42:43 cairo ntpd[24714]: time reset -190.225502 s
Dec 19 14:43:58 cairo ntpd[24714]: synchronized to 132.236.56.250,  
stratum 2
Dec 19 14:44:54 cairo ntpd[24714]: no servers reachable
Dec 19 14:52:49 cairo ntpd[24714]: synchronized to 66.33.216.11,  
stratum 2
Dec 19 14:52:53 cairo ntpd[24714]: no servers reachable
Dec 19 14:54:44 cairo ntpd[24714]: synchronized to 128.59.59.177,  
stratum 2
Dec 19 14:54:45 cairo ntpd[24714]: no servers reachable
Dec 19 14:54:57 cairo ntpd[24714]: synchronized to 66.92.250.40,  
stratum 2
Dec 19 14:55:45 cairo ntpd[24714]: no servers reachable
Dec 19 14:55:17 cairo ntpd[24714]: synchronized to 132.236.56.250,  
stratum 2
Dec 19 14:55:17 cairo ntpd[24714]: time reset -175.662019 s
Dec 19 14:56:32 cairo ntpd[24714]: synchronized to 132.236.56.250,  
stratum 2
Dec 19 14:57:25 cairo ntpd[24714]: synchronized to 66.33.216.11,  
stratum 2
Dec 19 14:57:25 cairo ntpd[24714]: synchronized to 206.111.81.7,  
stratum 2
Dec 19 14:57:27 cairo ntpd[24714]: no servers reachable
Dec 19 15:03:03 cairo ntpd[24714]: synchronized to 69.38.165.70,  
stratum 3
Dec 19 15:03:05 cairo ntpd[24714]: no servers reachable
Dec 19 15:03:08 cairo ntpd[24714]: synchronized to 128.59.59.177,  
stratum 2
Dec 19 15:03:59 cairo ntpd[24714]: synchronized to 132.236.56.250,  
stratum 2
Dec 19 15:04:03 cairo ntpd[24714]: no servers reachable
Dec 19 15:06:28 cairo ntpd[24714]: synchronized to 132.236.56.250,  
stratum 2
Dec 19 15:07:19 cairo ntpd[24714]: no servers reachable


Thanks,
Dan



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