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Old 02-28-2009, 02:47 AM
NoOp
 
Default NTP servers - was Kernel clock issue "Clocksource tsc unstable"

On 02/27/2009 07:36 PM, Ray Parrish wrote:
> NoOp wrote:
>> @Hal: next time, instead of rebooting (you'll still have to go to the
>> data center most likely), you might try
>> sudo /etc/network/if-up.d/ntpdate
>> first. If that resyncs the machine properly without the reboot, then you
>> might want to look into running ntp on those machines if you aren't
>> already. And if you are running ntp, have a look at the ntp source. You
>> can elect to have multiple sources; I use 0.us.pool.ntp.org and have
>> 1.us.pool.ntp.org as the backup. Just a thought...
>>
> Here are a few more time servers to try. 8-)
>
> server tick.usask.ca
> server tock.usask.ca
> server clock.tricity.wsu.edu
> server gilbreth.ecn.purdue.edu
> server molecule.ecn.purdue.edu
> server ntp.ubuntu.com
> server europium.canonical.com
>
> My system regularly connects to all of them. It's the way it was set up
> on install, as I haven't changed the configuration files for ntpd.
>
> Later, Ray Parrish
>

Yes, but I think that you may not be aware of the reasoning behind the
pool.ntp.org servers:

http://www.ntp.org/
http://www.pool.ntp.org/

which is ease the load on the big timeservers and spread the load over
many servers.

I also purposely remove the ntp.ubuntu.com/canonical servers; I' don't
mind providing some data, but sync'ing to them just seems a little big
brother/Microsoft'ish to me.




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Old 02-28-2009, 03:22 AM
Rashkae
 
Default NTP servers - was Kernel clock issue "Clocksource tsc unstable"

NoOp wrote:

>
> I also purposely remove the ntp.ubuntu.com/canonical servers; I' don't
> mind providing some data, but sync'ing to them just seems a little big
> brother/Microsoft'ish to me.
>
>

Unless you're doing something that's extremely time sensitive (such as
synchronizing to those time based RSA security tokens) I don't really
see the point to synchronizing with ntp at all. Any functioning clock
should be able to keep track of wall time within a few seconds accuracy
per month.

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Old 02-28-2009, 03:48 AM
Smoot Carl-Mitchell
 
Default NTP servers - was Kernel clock issue "Clocksource tsc unstable"

On Fri, 2009-02-27 at 23:22 -0500, Rashkae wrote:

>
> Unless you're doing something that's extremely time sensitive (such as
> synchronizing to those time based RSA security tokens) I don't really
> see the point to synchronizing with ntp at all. Any functioning clock
> should be able to keep track of wall time within a few seconds accuracy
> per month.

NTP synchronization is more important than you might realize. Weird
things can happen unless you keep the clocks synced between systems. If
you use NFS in your home network, you need to keep the systems in sync
or otherwise file update times can get out of wack which impacts
programs like make and rsync which depend on accurate file timestamps.
Also without time synchronization, log entries timestamp can be
inaccurate. Authentication systems like Kerberos depend on time
synchronization between systems as well.

All of these reasons may not be as critical for a home system or a
single desktop, but setting up NTP to use the pool.ntp.org servers is
easy and NTP requires few resources.

My own Internet facing server joined the pool.ntp.org system. If you
have a server which is on the net 24x7 and has reasonable bandwidth (1
mbs) I would urge you to join the pool. For more info on either joining
or using the pool see http://www.pool.ntp.org/
--
Smoot Carl-Mitchell
Computer Systems and
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cell: +1 602 421 9005

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Old 02-28-2009, 04:07 AM
NoOp
 
Default NTP servers - was Kernel clock issue "Clocksource tsc unstable"

On 02/27/2009 08:22 PM, Rashkae wrote:
> NoOp wrote:
>
>>
>> I also purposely remove the ntp.ubuntu.com/canonical servers; I' don't
>> mind providing some data, but sync'ing to them just seems a little big
>> brother/Microsoft'ish to me.
>>
>>
>
> Unless you're doing something that's extremely time sensitive (such as
> synchronizing to those time based RSA security tokens) I don't really
> see the point to synchronizing with ntp at all. Any functioning clock
> should be able to keep track of wall time within a few seconds accuracy
> per month.
>

Ah, but you are forgetting about a bad CMOS battery that doesn't keep a
bios clock updated. We've been through this before... via the thread.

Just a few months ago my daughter-in-law called and informed me that her
time was "off" and folks were complaining about the timestamps on her
emails. Of course it was an old system and the CMOS battery had spit the
dummy & I'd failed to set ntp up on the system during install.
The solution, until I could replace the battery, was of course to turn
on ntp and ensure that the system (it was Gutsy then) used ntp to sync.
I replaced the battery and all was fine. Note: I replaced the computer
(1.8Ghz) with a faster (2.4Ghz) system and now use the 1.8Ghz as a test
machine. It has no dmesg errors and uses tsc & seems to work just fine
w/without ntp, but my point is that a bad CMOS battery *can* indeed
cause clock issues.






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Old 02-28-2009, 04:47 AM
NoOp
 
Default NTP servers - was Kernel clock issue "Clocksource tsc unstable"

On 02/27/2009 08:48 PM, Smoot Carl-Mitchell wrote:

> All of these reasons may not be as critical for a home system or a
> single desktop, but setting up NTP to use the pool.ntp.org servers is
> easy and NTP requires few resources.
>
> My own Internet facing server joined the pool.ntp.org system. If you
> have a server which is on the net 24x7 and has reasonable bandwidth (1
> mbs) I would urge you to join the pool. For more info on either joining
> or using the pool see http://www.pool.ntp.org/

Indeed. The pool is the proper (IMO) way to use ntp for individual use &
works just fine. I've two systems w/side-by-side monitors and I can
adjust the time in either (one is always hardy, the other is test with
intrepid/whatever). I can watch the Ubuntu clocks on both and see the
change after the ntp updates/modify the clock on the test, even kill
ntpdate etc.



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Old 02-28-2009, 12:54 PM
Derek Broughton
 
Default NTP servers - was Kernel clock issue "Clocksource tsc unstable"

Rashkae wrote:

> NoOp wrote:
>
>>
>> I also purposely remove the ntp.ubuntu.com/canonical servers; I' don't
>> mind providing some data, but sync'ing to them just seems a little big
>> brother/Microsoft'ish to me.
>
> Unless you're doing something that's extremely time sensitive (such as
> synchronizing to those time based RSA security tokens) I don't really
> see the point to synchronizing with ntp at all. Any functioning clock
> should be able to keep track of wall time within a few seconds accuracy
> per month.

And on that note, I'll mention my most recent clock issues. After replacing
my laptop a couple of weeks ago, I was unable to immediately install Ubuntu
(only had hardy install disc, which didn't have kernel support for AHCI
disks - turned out all I really needed to do was change the BIOS setting
from AHCI to IDE, but I digress). So I installed Kubuntu 8.04 in a
VirtualBox, which automatically synchronizes the VM clock to the host. The
Windows host gets synchronized when I'm at a client's to their often-wrong
internal time server. Now, the VM runs all the things I always ran
natively, including an IMAP server (dovecot) which aborts about once a day
because Dovecot is paranoid about backward time changes, and shuts itself
down whenever that happens - and the default ntpdate setup on Ubuntu
resyncs every time a network device is upped.

So, I'd agree that ntp is serious overkill for most personal-use computers
and even ntpdate only needs to be run at boot (or resume-from-hibernate)
time. I would _always_ recommend syncing times at start-up, because some
hardware clocks are notoriously unreliable when the machine is powered
down.
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Old 02-28-2009, 01:06 PM
Derek Broughton
 
Default NTP servers - was Kernel clock issue "Clocksource tsc unstable"

Brian McKee wrote:

> On Fri, Feb 27, 2009 at 11:22 PM, Rashkae <ubuntu@tigershaunt.com> wrote:
>> NoOp wrote:
>>
>>>
>>> I also purposely remove the ntp.ubuntu.com/canonical servers; I' don't
>>> mind providing some data, but sync'ing to them just seems a little big
>>> brother/Microsoft'ish to me.
>
> as you wish - but I don't recall ntp sending any data the other way
> worth mentioning...

The fact that you continually connect is data. I can see his point - though
_I_ remove ntp.ubuntu.com because I've found it notoriously hard to
reach...

>> Unless you're doing something that's extremely time sensitive (such as
>> synchronizing to those time based RSA security tokens) I don't really
>> see the point to synchronizing with ntp at all. * Any functioning clock
>> should be able to keep track of wall time within a few seconds accuracy
>> per month.
>>
> You must have better quality systems than some of mine then - I've got
> units with good batteries that wander several minutes out of whack in
> a month without ntp all the time.

A few seconds/several minutes. Either way, it really isn't a big enough
deal to worry about, usually, but then I prefer to set my computers to
display analog clocks, because I don't like being too precise...

otoh, it seems to me that "ntp all the time" and "units with good batteries"
are conflicting criteria. If your system is _capable_ of getting the time
via ntp, then the clock is not running on the battery. The clock you're
seeing is the software clock, so if it's wandering while you're powered up
and not using ntp it's got nothing to do with the CMOS battery (and the hw
clock gets set from the sw clock on shutdown). If the clock only wanders
while you're powered off, then setting the sw clock at restart time via
ntpdate would be sufficient.
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Old 02-28-2009, 03:52 PM
Hal Burgiss
 
Default NTP servers - was Kernel clock issue "Clocksource tsc unstable"

On Sat, Feb 28, 2009 at 11:33:19AM -0500, Brian McKee wrote:
> Who cares when it wanders - on or off - I'd rather send one lousy UDP
> packet every once in a blue moon to my own router and keep everything
> actually at the right time. I just don't see why you WOULDN'T do it!

Amen. Give me precision over slop. As to anything functioning
as a server, you just *have* to have accurate time keeping.

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Old 02-28-2009, 04:03 PM
Kipton Moravec
 
Default NTP servers - was Kernel clock issue "Clocksource tsc unstable"

I have one computer in my network that is the time server. It goes out
and gets time from

0.us.pool.ntp.org
1.us.pool.ntp.org
2.us.pool.ntp.org
3.us.pool.ntp.org

Everyone else gets the time from my local time server. That includes the
windows computers.

So if the external network fails everything degrades together with my
network time server.

I am looking to hook up a GPS to the network time server. There is a way
to do it with the serial port, if your computer still has one.

Unfortunately I have FiOs with a dynamic IP address, otherwise I would
also serve time to the ntp.org pool. It is not much load on your network
or server. If you have a static IP address and a fast line, go for it.

--


Kipton Moravec AE5IB .- . ..... .. -...
==============================================
Four Way Test
Is it the Truth?
Is it Fair to all concerned?
Will it build Goodwill and Better Friendships?
Will it be Beneficial to all concerned?
- Herbert J Taylor (1932)




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Old 02-28-2009, 04:04 PM
Smoot Carl-Mitchell
 
Default NTP servers - was Kernel clock issue "Clocksource tsc unstable"

On Sat, 2009-02-28 at 09:54 -0400, Derek Broughton wrote:

> So, I'd agree that ntp is serious overkill for most personal-use computers
> and even ntpdate only needs to be run at boot (or resume-from-hibernate)
> time. I would _always_ recommend syncing times at start-up, because some
> hardware clocks are notoriously unreliable when the machine is powered
> down.

On my home LAN, all my clients synchronize their clocks to my Internet
facing server which broadcasts time packets on the internal LAN every 30
seconds. It keeps all the clocks within milliseconds of each other and
it is easy to setup internal clients. I have several MacOS boxes
syncing this way plus my Ubuntu notebook. If you rove a lot with your
notebook, I would suggest syncing to pool.ntp.org. But I agree in lieu
of the above, syncing at boot with ntpdate makes sense.

NTP is just not that traffic or resource intensive. It also does not
make sudden backward or forward time jumps. It will slew the clock
slowly to bring it into sync. What this means is time always moves
incrementally forward. The software clock never jumps suddenly back in
time.
--
Smoot Carl-Mitchell
Computer Systems and
Network Consultant
smoot@tic.com
+1 480 922 7313
cell: +1 602 421 9005

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