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 <[email protected]> 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 <[email protected]> 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 >>> <[email protected]> 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? >>> >>> Sent with [ProtonMail](https://protonmail.com) Secure Email. >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>> and follow the instructions there. >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
