ntp to sync clocks

shoulda closed this.

why not just run NTP continuously rather than daily? that way they are never out of sync!

'cuz I tried running ntpd, and it'd just deer-in-headlights for me and not actually do anything. ntptimeset was the only thing I could get working.

be my guest...

matt-the-sysadmin recently jumped through his ass to get ntpd working for his day job, and has generously offered to get our boxen set up corectly, instead of my cronjob hack.

Werken's buying him Thai on Wednesday to compensate.

Heya,

I think I've completed the NTP stuff, at least mostly. However, there's
a test that should be performed before I do the last thing or two: please
reboot stout and make sure he comes back to life properly.

Here's the run-down...

falstaff is your local time master. He synchronizes off three of the
best public NTP servers out there. ale and stout synchronize off of
falstaff.

All three beers use actual NTP (ntpd) to do their synch; no more
ntptimeset or whatever.

All three also dump their system time into the hardware clock once a
day so that recovery from a power failure will put them at least close
to right. That's in root's crontab.

On boot, each system should use ntpdate to grab the current time and
slam it into the clock. No skew; slam. Boom: the time is now Right.
I've built something that should do this. It's on stout, which is why
he should be rebooted. If it works, I'll enable it on the others.

The ntpd is running out of rc.local on all systems. Screw all that
init.d crap, and screw RedHat, and screw their idea of how ntpd should
run (which, by the way, was wrong).

I have falstaff broadcasting ntp version 4 time packets onto the wire.
This might synchronize the Mac and/or the Tivo; it depends on whether
they listen and, if so, to what version. I didn't sniff that out, but
can if you want. If the periodic blinkenlight bothers you, commend out
the "broadcast" line in falstaff:/etc/ntp.conf, kill that ntpd, and run
it again with '/usr/sbin/ntpd -U ntp'.

How do you know if it's working? Well, you can get the date on all
systems and see how close they are. You also can use ntpq, which
works basically like this (as seen from stout):

root@stout# ntpq -p falstaff
remote refid st t when poll reach delay offset jitter
==============================================================================
10.42.42.255 0.0.0.0 16 - - 64 0 0.000 0.000 4000.00
*ntp2.usno.navy. .USNO. 1 u 63 64 177 67.106 22.187 29.521
+ns2.usg.edu .GPS. 1 u 56 64 377 56.014 19.927 5.886
+cuckoo.nevada.e time.nist.gov 2 u 4 64 377 96.637 24.512 3.470

root@stout# ntpq -p ale
remote refid st t when poll reach delay offset jitter
==============================================================================
*falstaff ntp2.usno.navy. 2 u 56 64 177 0.189 -0.416 8.265

root@stout# ntpq -p stout
remote refid st t when poll reach delay offset jitter
==============================================================================
falstaff ntp2.usno.navy. 2 u 34 64 7 0.177 -11.116 5.666

The * items are in use (time is in synch). The + items are potential: if
a * goes away, it'll fall back to the +. ale is in synch with falstaff.
stout isn't. It takes about 5-8 minutes (I think--haven't measured) for
these things to decide to synch up. (stout synched up.)

The ntpdate program is another good one for testing; use "-d" to keep it
from actually changing your clock. 'ntpdate -d falstaff' will report on
how things are on falstaff.

I've made a dinky little script on falstaff called "checktime" that'll
give you a quick report:

[root@falstaff bin]# ./checktime
on 10.42.42.42 offset is 0.000002 seconds at 22 Jul 23:45:17
on 10.42.42.51 offset is -0.008236 seconds at 22 Jul 23:45:18
on 10.42.42.52 offset is 0.020758 seconds at 22 Jul 23:45:18

Not surprisingly, falstaff is pretty much in synch with himself (line 1).

So... I think that's it. If you add nodes, either copy stuff over or
yell and I will. For "good enough for now" type service on those new
nodes, I'd cron this:

*/10 * * * * /usr/bin/ntpdate 10.42.42.42 > /dev/null 2>&1

-Matt

everything's syncing.