ntp logic ..

[someone_4]

Hello everyone and Happy Holidays !

My question today has to do with ntp logic.Ok here we go ..
We have 1 server (lvadm01) going out to the internet to clock.isc.org. And I was going around to all my servers to check to see what time server they were synced up to. Most of them were synced to lvadm01. But I found one server lvscu1 that is synched to lvapp10 that is synched to lvadm01. As you see the ntpq ???p out put below.

remote refid st t when poll reach delay offset disp
==============================================================================
*lvapp10.prod.ne lvadm01.admin.n 4 u 87 128 377 0.37 0.081 0.06


(NET-lvapp10) /# ntpq -p
remote refid st t when poll reach delay offset disp
==============================================================================
*lvadm01.admin.n clock.isc.org 3 u 874 1024 377 0.41 -0.059 0.08



My question is that lvscu1 is synched up to lvapp10 that is synched up to lvadm01 in a daisy chain type fashion. Now is that the correct way to do it? Or do I want lvscu1 directly to lvadm01 ? Or does it matter ? What is the difference if any?

Thanks
~ Richard

[Pete Randall]

Richard,

It's primarily a matter of semantics. It works whether you call it a horse or a pony. The difference is most likely completely un-noticeable.

Pete

[Jeff Schussele]

Hi Richard,

Shouldn't be a problem.
But what I would do is set lvapp10 up to be a peer to lvadm10 in all the clients & have lvapp10 sync to clock.isc.org. That way if lvadm10 has to go down for maint, the clients still have an ntp server available. Actually this is the preferred way to do this - you know not having all your eggs in one basket & all.

Rgds,
Jeff

[John Bolene]

It just puts another link in the chain, no big deal.

I have mine setup so that one server (1st) has access to the internet to get time, and another server (2nd) gets its time from the 1st one.

All the rest of the servers use both as a reference with the primary being the 1st and the other being the 2nd.

One or the other of the servers is up at all times.

[Bill Hassell]

NTP is an incredibly robust piece of software which can maintain a chain (called stratum levels in NTP) of 5-10 computers with NO loss in precision (ie, maintains at least 128ms accuracy at every level of the chain).

Having a single Internet source is probably not the best solution. Pick about 5 or 6. NTP will do an intelligent poll of each server and if any begin to drift from the others, those servers won't have any effect on the actual time. Total loss of the source is not a bad thing as the server will just continue until the source comes back, and even then, time is changed very slowly to prevent losing or gaining a single second.