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?
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‐‐‐‐‐‐‐ 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?
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