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Old 12-05-2008, 10:41 AM   #1
helptonewbie
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Strange Problem with the Clock


Hi All,
I Have ntp set-up on SLES10 which is working fine, but strange problem i've not come across with clock syncs before.

in Shell type:-
SERVER # date
Fri Dec 5 16:32:55 GMT 2008

SERVER # hwclock
Thu Jul 22 19:54:21 2010 -0.000407 seconds

Then if i 'cat' my firewall entries... I've got iptables logging to a file. I force a filter that triggers iptables to log an occurrence and the time for that occurrence is also completely different.
Dec 5 10:27:42

(Baring in mind all these are done within a few seconds of each other..)

What could be up? The output of 'date' is as it should be, the date and time settings are set to UTC and i've set the GMT time Saving as i want it (to London Greenwich). iptables looks to be just getting the wrong daylight time somehow and hwclock... well i haven't re-booted the server PLUS i haven't forced the clock to sync to hardware clock yet but i can. Perhaps that is the problem?

Cheers,
MJ
 
Old 12-05-2008, 12:46 PM   #2
TB0ne
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Quote:
Originally Posted by helptonewbie View Post
Hi All,
I Have ntp set-up on SLES10 which is working fine, but strange problem i've not come across with clock syncs before.

What could be up? The output of 'date' is as it should be, the date and time settings are set to UTC and i've set the GMT time Saving as i want it (to London Greenwich). iptables looks to be just getting the wrong daylight time somehow and hwclock... well i haven't re-booted the server PLUS i haven't forced the clock to sync to hardware clock yet but i can. Perhaps that is the problem?
That's what I'd suggest first, is to sync the hardware clock to your system clock.

Also, is this a VM machine by any chance? There is a known problem with VMware linux guests that causes the system clock to skew. A kernel patch is required to fix that. Or, if you have to stay in production you can just have a small CRON job to run "ntpdate" against your time server every five minutes...
 
Old 12-05-2008, 12:55 PM   #3
helptonewbie
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Thanks for the info Tbone, i did already go ahead and run that sync which of course would update the harware clock as expected. However no change at all occurred to the time that i saw with iptables logs... Very strange, does sugest some kind of daylight saving issue but damned if i know why thats playing about. Another server exactly the same is working fine.

No not a VMware server... but i didn't know of that issue as i do use VMs and not come across that issue yet... thanks for the heads up on that, i will look into it just in case. OR i have come across it before and it was nothing that ntp couldn't fix for me... anyway i'll double check that.

Ant ideas on the iptables problem would be great.

Thanks
MJ
 
Old 12-05-2008, 07:22 PM   #4
ozminh
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try this
hwclock -w or hwclock --systohc
hwclock -s or hwclock --hctosys
 
Old 12-06-2008, 05:02 AM   #5
helptonewbie
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Thanks for the reply... i gave it a go but nothing changed... Its out by exactly 6 hours which is why it must be something to do with daylight savings and unlikely to be down to skew. I mean its iptables logs i see that the time is out... looking at something like /var/log/messages i can see the correct time for new log entries. So it may just be iptables specifically but still i don't understand why

Cheers,
MJ

Last edited by helptonewbie; 12-06-2008 at 05:06 AM.
 
  


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