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?
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‐‐‐ Original Message ‐‐‐
On Monday, 22 July 2019 г., 17:38, Taka Kamiya 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
> 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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