[time-nuts] Noob question, NTP stratum 1.

[Bob kb8tq]

Hi

One of the gotcha’s with “cell phone” based timing is discovering that the provider
has been a bit lax about making sure the time stamp on the signal is what it should 
be. The problem is less common with 800 MHz CDMA than other bands / services. 
One of the reasons we see a lot of this sort of gear on the secondary market is that
… errr …. they had problems ….  ( = trust but verify ….)

Bob

> On Jul 22, 2019, at 7:38 PM, K5ROE Mike <K5ROE at roetto.org> wrote:
> 
> You may want to look at something an Endrun CDMA ntpserver for the datacenter; don't need view of the sky. Available on the used market sub $1k
> 
> Standard solution for this scenario.
> 
> 
> K5ROE Mike
> 
> On 7/22/19 10:50 AM, wildylion via time-nuts wrote:
>> Yeah, of course I will NOT do anything home-grown for the datacenter.
>> 
>> But currently it uses 3 Stratum 2 NTP servers, one per DC, with them referencing a list of 4 close-by Stratum 1 sources.
>> 
>> ntpstat generally says that time is correct within ~50 ms, while jitter and offset generally don't exceed 1ms, the root dispersion is quite large.
>> Also these Stratum 2 NTPs are run from Cisco routers, which I doubt are very good at timekeeping.
>> 
>> When I implemented this scheme, I offered to have S2 on a set of x86 servers, but was overruled by management who said it'll be better if we run S2's off Cisco gear.
>> 
>> So what if we add a couple GPSDO's into the mix, using them as primary time sources alongside public Stratum1 NTP servers for sanity check? And of course moving the S2's to something more stable.
>> 
>> My own, homegrown S1 pool NTP is another matter entirely - I think just a tuned Raspi with a M8N will be enough?
>> 
>> Sent with [ProtonMail](https://protonmail.com) Secure Email.
>> 
>> ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
>> On Monday, 22 July 2019 г., 17:38, Taka Kamiya <tkamiya9 at yahoo.com> wrote:
>> 
>>> If you have 100 production servers with database, I am going to strongly discourage you from taking a "home grown" route.  You will need multiple redundant implementation with fail-over.  You mentioned budget.  How much are your bosses willing to pay for consultation fees for failed or corrupted data?  I am assuming you are talking about Oracle RDBMS with minimum of 2 way RAC.
>>> 
>>> If you are using collocation services, doesn't the center itself offer ntp service for fee?
>>> 
>>> If you need 24 hour hold-over, I will take nothing less than multiple ovenized crystal OSC GPSDO with redundancy per center.  Then feed that into ntp server with multi-location fail over.
>>> 
>>> If I were responsible for managing such system and if my boss will want me to go cheap route, I will seriously fight it.  If it's successful, your boss will get credit for spending little and getting a big benefit.  WHEN it fails, it's going to be your fault for not mitigating risk sufficiently.  Try pricing out 2 days of consulting fees....
>>> 
>>> ---------------------------------------
>>> (Mr.) Taka Kamiya
>>> KB4EMF / ex JF2DKG
>>> 
>>> On Monday, July 22, 2019, 10:05:56 AM EDT, wildylion via time-nuts <time-nuts at lists.febo.com> wrote:
>>> 
>>> Hello there,
>>> 
>>> I wanted to ask for advice regarding NTP
>>> 
>>> Situation 1:
>>> What I currently have is a uBlox M8N GPS puck I'm planning to use with the Raspberry PI. Seems like it should work almost out of the box with some kernel tuning, but I have a question about short term stability in the event of GPS loss - how well will the board hold over if it's lost GPS for, say, 24 hours?
>>> 
>>> Situation 2:
>>> Also, there's a need for more dependable NTP time sources for our colocated spaces.
>>> 
>>> What we have is about 100 servers, some of them running DBMS that wouldn't like clock drift at all. After a recent incident involving NTP I've got an idea to install GPSDO time servers in each datacenter and slave them to stratum2's that will be actually distributing time to clients.
>>> 
>>> All the certified GNSS disciplined clocks are really expensive (way more than the management would approve), so what I'm planning to do is possibly getting a couple LeoNTP units and using them as the root time sources, would this be a good plan? Of course, all the NTP infrastructure will be monitored, and possibly we'll use Stratum 2 servers which would be slaved to GPSDO S1's AND the public NTP pool for sanity checks.
>>> 
>>> Maybe BG7TBL's units instead of LeoNTP?
>>> Is that a good idea?
>>> 
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