Re: ntp problem: the server clock slowly recedes
2011/8/9 Stan Hoeppner <stan@hardwarefreak.com>:
> On 8/9/2011 6:28 AM, owl700@gmail.com wrote:
>
>> Hi Stan, thanks for your reply, we have a bare metal host hp dl580g7 no VM guest
>>
>> After this post we have add nomodify at localhost lines and offset
>> seems acceptable now
>
> It *seems* acceptable because you just restarted ntpd. Watch 'ntpq -p'
> for 3 days and those numbers will be right back up they were. I have
> one old self built 2-way SMP system (non NUMA) that keeps incredibly
> accurate time, currently up for 43 days, due to new kernel installation.
> It was up for 181 days prior to that.
Berfore inserting nomodify the clock lost 2 minutes in 1 hour, now is
stable, i can't hunderstand how can localhost modify ntpd but this was
the only explanation, can you help me hunderstand?
remote refid st t when poll reach delay offset jitter
==============================================================================
xntp1.inrim.it .CTD. 1 u 22 64 377 23.785 432.491 134.794
*ntp2.inrim.it .CTD. 1 u 32 64 377 25.653 221.217 130.149
+alarich.online- 192.53.103.108 2 u 39 64 377 67.928 300.899 75.004
+ntps1-0.cs.tu-b .PPS. 1 u 41 64 373 57.509 217.705 117.816
>
>> # Local users may interrogate the ntp server more closely.
>> restrict 127.0.0.1 nomodify
>> restrict ::1 nomodify
>>
>> mcube@ssh-player:~$ ntpq -p
>> remote refid st t when poll reach delay offset jitter
>> ==============================================================================
>> *ntp1.inrim.it .CTD. 1 u 131 64 376 23.940 478.163 144.085
>> +ntp2.inrim.it .CTD. 1 u 6 64 375 25.877 540.437 173.659
>> +alarich.online- 192.53.103.108 2 u 64 64 377 70.188 511.878 145.782
>> +ntps1-0.cs.tu-b .PPS. 1 u 60 64 337 57.674 513.015 167.303
>>
>>
>> Do you think there is a HW clock problem?
>
> My old 2-way:
>
> remote refid st t when poll reach delay offset jitter
> ========================================================================
> *navobs1.wustl.e .GPS. 1 u 452 1024 377 63.322 -3.093 1.269
> +ntp.okstate.edu .USNO. 1 u 135 1024 377 73.731 1.812 1.889
> +tick.uh.edu .GPS. 1 u 759 1024 257 78.868 1.829 1.288
>
> Linux greer 2.6.38.6 #2 SMP Tue May 17 23:54:39 CDT 2011 i686 GNU/Linux
> 06:47:26 up 43 days, 4:56, 2 users, load average: 0.01, 0.04, 0.06
>
> I run a custom kernel, rolled from vanilla kernel.org source, on this
> Squeeze system. It has no time keeping tweaks nor custom kernel boot
> parameters. Note my offset and jitter compared to yours. I've had
> uptimes of 300+ days with offset and jitter no different that at 1 day
> of uptime.
>
> To answer your question, you need to determine if the Linux kernel is at
> fault. Try a different clock source. Clock sources can be changed at
> runtime by writing the new clocksource name to the file
> /sys/devices/system/clocksource/clocksource0/current_clocksource
> but be aware that changing to an unstable/broken clock source can hang
> the system. Changing tsc or jiffies to acpi_pm should be okay. (The list
> of available sources is in the file available_clocksource in the same
> directory.)
I think this isn't a good idea in my case i can't access the server
directly if it hangs
I had change in ntp.conf ntp servers but same problem
> If changing the clock source helps, you'll need to add a boot parameter
> to grub to make it permanent. See section "Timer-Specific Options" in
> this document:
> www.kernel.org/pub/linux/kernel/people/gregkh/lkn/lkn_pdf/ch09.pdf
>
> Given that this is a DL580 system I doubt it's faulty hardware, although
> it's possible. Assuming the hardware is ok, I'm surprised a default
> Debian kernel won't keep time accurately on it. Google didn't spit back
> any such Debian+DL580 clock issues...
I have a hp DL360 with same kernel, same squeeze 64bit etc. and there
aren't any issues with ntp how you can see
remote refid st t when poll reach delay offset jitter
==============================================================================
*ntp1.inrim.it .CTD. 1 u 168 1024 377 24.407 -0.040 0.189
+ntp2.inrim.it .CTD. 1 u 580 1024 377 23.556 0.105 0.09
Before last sunday the hp dl580 don't had this ntp problem
> --
> Stan
>
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