| 1 |
On 17/03/16 20:26, Alan McKinnon wrote: |
| 2 |
> On 17/03/2016 08:50, Håkon Alstadheim wrote: |
| 3 |
>> I have a server SUPPOSED to be running 24/7, but every once in a while |
| 4 |
>> during a prolonged absence the box will go down. The Real Time Clock |
| 5 |
>> will drift, and in the rush to get the box up again I let everything |
| 6 |
>> boot up automatically and get both wrong time on the main systems, and |
| 7 |
>> different times on the various systems. |
| 8 |
>> |
| 9 |
>> My setup has a main server which does NTP, but with no direct link to |
| 10 |
>> the outside. Router&firewall /have/ to be booted booted later (dumb |
| 11 |
>> setup, don't ask), after which I can finally get correct time from NTP. |
| 12 |
>> |
| 13 |
>> NTP initiates "11 minute mode", which makes /etc/adjtime useless as far |
| 14 |
>> as I understand. Anybody have a /correct/ way to account for RTC drift |
| 15 |
>> on a box running ntpd? Right now I have a ---file in |
| 16 |
>> /etc/cron.d/time-bad like so: |
| 17 |
>> * * * * * root adjtimex -S 5 >/dev/null 2>&1 </dev/null |
| 18 |
>> --- |
| 19 |
>> |
| 20 |
>> Combined with an old-fashioned setup for hwclock during boot and |
| 21 |
>> shutdown. This feels really wrong, and I have no idea what I am doing. |
| 22 |
>> |
| 23 |
>> TLDR: Anybody have a /correct/ way to account for RTC drift on a box |
| 24 |
>> running ntpd? |
| 25 |
>> |
| 26 |
>> |
| 27 |
> |
| 28 |
> |
| 29 |
> When the box was off, all questions of accurate ntp tracking are moot. |
| 30 |
> ntp is designed around the idea that every second happens but from your |
| 31 |
> machine's point of view they didn't happen since it was powered down. |
| 32 |
> |
| 33 |
> I would go the really simple route and force ntpdate to run once during |
| 34 |
> boot up before ntpd is started, thereby avoiding the entire issue. |
| 35 |
> Sometimes correctness really doesn't matter, this looks like one of those. |
| 36 |
> |
| 37 |
> |
| 38 |
> alan |
| 39 |
> |
| 40 |
|
| 41 |
add a cheap gps setup as the reference clock to the server, or even |
| 42 |
better is a dedicated time server (either a real one or a raspberry |
| 43 |
pi/gps) on the network if you have internal connectivity. Going super |
| 44 |
cheap, but not quite as accurate for me was an arduino and rtc on a |
| 45 |
bluetooth pan for when the network was down but I needed a reference (to |
| 46 |
power up the real server :). |
| 47 |
|
| 48 |
|
| 49 |
google "arduino time server" for plenty of options :) |
| 50 |
|
| 51 |
BillK |
Archives