[ntp:questions] ntpd, boot time, and hot plugging

David L. Mills mills at udel.edu
Mon Feb 7 04:10:08 UTC 2005


There are quite a number of things that get reported to the system log, 
like clock steps, KoDs, crypto lockup, etc. A list of system log 
messages is in the documentation. At least in our shop the logs are 
automatically retrieved and scanned once per day looking for attention 
messages. In the general scheme of things, it doesn't matter a lot, once 
the frequency has converged, for a workstation client to go a day 
without juice. If one of the NIST ntpd servers comes bum, Judah gets 
instantly beeped. Now that's real dedication.

Well, I don't know about missiles, but I do know NTP is on the Space 
Shuttle and Aegis cruiser fleet and will be on the DDX destroyer fleet.


Brad Knowles wrote:
> At 9:43 PM -0200 2005-02-06, Alain wrote:
>>  This requires that I have another daemon taking care of this one! Just
>>  to see if I have to Start ntpd -g again... If it makes sense for you,
>>  I cannot see it. I undertsand that I am just a newcomer and as such my
>>  opinions have little weight. I am conciouns that here I am just a user
>>  and as such I have the priviledge of asking silly questions :)
>     At some point, the software is going to run into a problem that it 
> can't correct.  It's going to be faced with some sort of input that it 
> doesn't know how to deal with.  In that situation, what do you do?
>     Do you freak out and set the clock back to zero, in the hopes that 
> something will break really, really badly and someone will notice?  What 
> if they don't notice?  Do you do some other horribly destructive things, 
> in hopes that someone will notice?  What if you've done every 
> destructive thing you can think of (including wiping and doing a 
> low-level format of all attached hard drives), and still no one 
> notices?  What happens if the system that fails is part of a nuclear 
> missile guidance or launching system?  Do you really want them doing 
> destructive things on their own, hoping to be able to catch the 
> attention of the operator?
>     Do you log an error in the syslog and exit?  This is the approach 
> taken by most Unix-style daemons, and part of the deal is that you've 
> got to watch them to make sure that this hasn't happened.  There's 
> little difference here between how ntpd works as any other.  If you're 
> not doing this kind of monitoring already for all the other important 
> processes on the system, that's a much bigger problem that you've got to 
> resolve.

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