| Re: [chrony-users] reachability cycling between 377 to 000 |
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All:
If I monitor the output from 'chronyc sources', I see the reachability status
change regularly from "377" to "000" and back again. Is this a known problem or
a wrong / incomplete configuration?
After starting 'chronyd', the reachablilty goes from 0 to 377 as expected. 12
minutes (+/-1 poll interval) after "377", reachability starts dropping every 16
s poll interval (376, 374, 370, ...) down to 000. There it stays for 12 minutes,
at which point reachability starts ascending (000, 003, 007, ...) back to 377.
The process then repeats. Typical data from ‘chronyc -s’ is shown below.
That means that chrony stopped being able to reach the source. It is a byte
where the bits are moved over (to the high bit) and the lowest bit is replaced
by 1 if the source was reached and by 0 if not. Ie, the lowest bit always
shows the reachability of the source at the last attempt, the next lowest the
reachability on the second last attempt, etc.
I'm using a Raspberry Pi 4B and Uputronics GPS HAT (uBlox 8) with 'gpsd'
(versions shown below). I built it following the instructions on the NTPSEC
documentation page, “Stratum-1-Microserver HOWTO”. This includes stripping
non-essential (for NTPSEC) services. Details, including ‘ps’ output for
‘chronyd’ and ‘gpsd’ are below.
Sounds like a problem with gpsd. Or with the card.
'cgps -s' shows nothing obviously wrong to my eye. I have a cheapo puck antenna
in the window with mostly south exposure. Capturing NMEA GGA sentences as close
as possible to the reachability changes always shows a lock at that time (field
5, "FS Fix Status).
This setup runs 'ntpsec' as expected, with perhaps a little more jitter than I'd
like. There is no change in reachability once 377 is achieved at startup.
Thanks for any ideas for fixing or further troubleshooting.
-wis
Test Setup
RPI 4B with 2GB RAM and latest firmware, Uputronics GPS HAT (uBlox 8)
-----------------------
wis@raspberrypi:~ $ cat /proc/cpuinfo | perl -ane 'next if( !
/(Revision|Hardware)/m); print'
Hardware : BCM2711
Revision : b03111
wis@raspberrypi:~ $ uname -a
Linux raspberrypi 5.4.51-v7l+ #1333 SMP Mon Aug 10 16:51:40 BST 2020 armv7l
GNU/Linux
wis@raspberrypi:~ $ chronyd -v
chronyd (chrony) version 3.5.1 (+CMDMON +NTP +REFCLOCK +RTC +PRIVDROP -SCFILTER
-SIGND +ASYNCDNS -SECHASH +IPV6 -DEBUG)
wis@raspberrypi:~ $ gpsd -V
gpsd: 3.21.1~dev (revision release-3.21-191-ge80e4bd75)
wis@raspberrypi:~ $ sudo rpi-eeprom-update
BCM2711 detected
Dedicated VL805 EEPROM detected
BOOTLOADER: up-to-date
CURRENT: Thu 03 Sep 2020 12:11:43 PM UTC (1599135103)
LATEST: Thu 03 Sep 2020 12:11:43 PM UTC (1599135103)
FW DIR: /lib/firmware/raspberrypi/bootloader/critical
VL805: up-to-date
CURRENT: 000138a1
LATEST: 000138a1
wis@raspberrypi:~ $ ps -aux | grep sbin/gpsd | grep -v grep
nobody 426 0.1 0.0 11776 1664 ? S<sl Oct10 7:56
/usr/local/sbin/gpsd -P /var/run/gpsd.pid /dev/gpsd0
wis@raspberrypi:~ $ ps -aux | grep sbin/chronyd | grep -v grep
root 19180 0.8 0.0 12396 1864 ? S 09:12 4:10
/usr/local/sbin/chronyd
wis@raspberrypi:~ $ gpsd/ubxtool -p MON-VER -P 18.00
ubxtool: poll MON-VER
sent:
UBX-MON-VER:
Poll request
...
UBX-MON-VER:
swVersion ROM CORE 3.01 (107888)
hwVersion 00080000
extension FWVER=SPG 3.01
extension PROTVER=18.00
extension GPS;GLO;GAL;BDS
extension SBAS;IMES;QZSS
...
-----------------------
data ( "chronyc -s | grep PPS", captured when reachability changes, followed by
"gpspipe -r -t -n 13 | grep GGA", both within a perl script with some line
editing for clarity and calculating the delta T between changes in the last
column. The next to last column is the "fix" status in the GGA NMEA sentence, 1:
GPS fix, 2: DGPS fix ).
wis@raspberrypi:~ $ tail -50 chrony_mon
2020-10-15T15:00:21 #* PPS 0 4 200 124 -231 ns[
-364 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T15:00:37 #* PPS 0 4 0 139 -231 ns[
-364 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T15:12:21 #* PPS 0 4 1 4 +30 ns[
+8058 ns] +/- 444 ns GGA lock: 2 11:44
2020-10-15T15:12:37 #* PPS 0 4 3 8 -14 ns[
-25 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T15:12:53 #* PPS 0 4 7 8 +147 ns[
+234 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T15:13:09 #* PPS 0 4 17 7 -48 ns[
-65 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T15:13:25 #* PPS 0 4 37 7 +272 ns[
+346 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T15:13:41 #* PPS 0 4 77 8 -216 ns[
-264 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T15:13:57 #* PPS 0 4 177 9 +2 ns[
+2 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T15:14:13 #* PPS 0 4 377 7 +462 ns[
+539 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T15:26:29 #* PPS 0 4 376 28 -584 ns[
-672 ns] +/- 444 ns GGA lock: 2 12:16
2020-10-15T15:26:45 #* PPS 0 4 374 44 -584 ns[
-672 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T15:27:01 #* PPS 0 4 370 60 -584 ns[
-672 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T15:27:17 #* PPS 0 4 360 76 -584 ns[
-672 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T15:27:33 #* PPS 0 4 340 92 -584 ns[
-672 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T15:27:49 #* PPS 0 4 300 108 -584 ns[
-672 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T15:28:05 #* PPS 0 4 200 124 -584 ns[
-672 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T15:28:21 #* PPS 0 4 0 140 -584 ns[
-672 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T15:40:21 #* PPS 0 4 1 11 -37 ns[
-7074 ns] +/- 444 ns GGA lock: 2 12:00
2020-10-15T15:40:37 #* PPS 0 4 3 7 -5 ns[
-88 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T15:40:53 #* PPS 0 4 7 7 -382 ns[
-594 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T15:41:09 #* PPS 0 4 17 6 +105 ns[
+141 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T15:41:25 #* PPS 0 4 37 8 -177 ns[
-225 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T15:41:41 #* PPS 0 4 77 7 -110 ns[
-134 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T15:41:57 #* PPS 0 4 177 6 -307 ns[
-365 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T15:42:13 #* PPS 0 4 377 7 -167 ns[
-194 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T15:54:13 #* PPS 0 4 376 29 -83 ns[
-115 ns] +/- 543 ns GGA lock: 2 12:00
2020-10-15T15:54:29 #* PPS 0 4 374 45 -83 ns[
-115 ns] +/- 543 ns GGA lock: 2 00:16
2020-10-15T15:54:45 #* PPS 0 4 370 61 -83 ns[
-115 ns] +/- 543 ns GGA lock: 2 00:16
2020-10-15T15:55:01 #* PPS 0 4 360 77 -83 ns[
-115 ns] +/- 543 ns GGA lock: 2 00:16
2020-10-15T15:55:17 #* PPS 0 4 340 93 -83 ns[
-115 ns] +/- 543 ns GGA lock: 2 00:16
2020-10-15T15:55:33 #* PPS 0 4 300 109 -83 ns[
-115 ns] +/- 543 ns GGA lock: 2 00:16
2020-10-15T15:55:49 #* PPS 0 4 200 125 -83 ns[
-115 ns] +/- 543 ns GGA lock: 2 00:16
2020-10-15T15:56:05 #* PPS 0 4 0 141 -83 ns[
-115 ns] +/- 543 ns GGA lock: 2 00:16
2020-10-15T16:07:49 #* PPS 0 4 1 9 -57 ns[
-1228 ns] +/- 444 ns GGA lock: 2 11:44
2020-10-15T16:08:05 #* PPS 0 4 3 7 -26 ns[
-73 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T16:08:21 #* PPS 0 4 7 9 -98 ns[
-149 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T16:08:37 #* PPS 0 4 17 8 -13 ns[
-33 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T16:08:53 #* PPS 0 4 37 8 -336 ns[
-428 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T16:09:09 #* PPS 0 4 77 7 +499 ns[
+610 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T16:09:25 #* PPS 0 4 177 9 +41 ns[
+50 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T16:09:41 #* PPS 0 4 377 8 -50 ns[
-58 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T16:21:41 #* PPS 0 4 376 28 -400 ns[
-522 ns] +/- 444 ns GGA lock: 2 12:00
2020-10-15T16:21:57 #* PPS 0 4 374 44 -400 ns[
-522 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T16:22:13 #* PPS 0 4 370 60 -400 ns[
-522 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T16:22:29 #* PPS 0 4 360 76 -400 ns[
-522 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T16:22:45 #* PPS 0 4 340 92 -400 ns[
-522 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T16:23:01 #* PPS 0 4 300 108 -400 ns[
-522 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T16:23:17 #* PPS 0 4 200 124 -400 ns[
-522 ns] +/- 444 ns GGA lock: 2 00:16
2020-10-15T16:23:33 #* PPS 0 4 0 140 -400 ns[
-522 ns] +/- 444 ns GGA lock: 2 00:16
‘cgps -s’ output
┌──────────────────────────────────────
?? ??────┐┌──────────────────Seen 24/Used 11┐
│ Time: 2020-10-16T00:45:08.000Z (18)││ PRN Elev Azim SNR
Use │
│ Latitude: <masked> N ││GP 3 64.0 177.0 25.0
Y │
│ Longitude: <masked> W ││GP 4 71.0 325.0 33.0
Y │
│ Alt (HAE, MSL): 406.827, 482.211 ft ││GP 6 21.0 301.0 31.0
Y │
│ Speed: 0.01 mph ││GP 7 13.0 231.0 29.0
Y │
│ Track (true, var): 12.3, 14.7 deg ││GP 9 35.0 290.0 28.0
Y │
│ Climb: 0.00 ft/min ││GP 16 37.0 125.0 37.0
Y │
│ Status: 3D DGPS FIX (2 secs) ││GP 22 42.0 166.0 29.0
Y │
│ Long Err (XDOP, EPX): 0.51, +/- 6.4 ft ││GP 26 39.0 75.0 30.0
Y │
│ Lat Err (YDOP, EPY): 0.65, +/- 8.7 ft ││GP 31 14.0 52.0 21.0
Y │
│ Alt Err (VDOP, EPV): 1.41, +/- 21.9 ft ││GL 71 44.0 110.0 21.0
Y │
│ 2D Err (HDOP, CEP): 0.88, +/- 13.4 ft ││GL 73 43.0 41.0 13.0
Y │
│ 3D Err (PDOP, SEP): 1.66, +/- 138 ft ││GP 1 2.0 198.0 0.0
N │
│ Time Err (TDOP): 0.87 ││GP 2 1.0 338.0 0.0
N │
│ Geo Err (GDOP): 1.88 ││SB 46 39.0 189.0 0.0
N │
│ ECEF X, VX: -2505536.420 m 0.010 m/s ││SB 48 38.0 194.0 0.0
N │
│ ECEF Y, VY: -3848833.310 m -0.020 m/s ││SB 51 37.0 158.0 0.0
N │
│ ECEF Z, VZ: 4411330.600 m 0.000 m/s ││GL 65 31.0 317.0 0.0
N │
│ Speed Err (EPS): +/- 1.0 mph ││GL 72 71.0 n/a 0.0
N │
│ Track Err (EPD): +/- 193 deg ││GL 74 73.0 155.0 0.0
N │
│ Time offset: 0.471591566 s ││GL 75 19.0 199.0 0.0
N │
│ Grid Square: <masked> ││GL 81 8.0 345.0 0.0
N │
└──────────────────────────────────────
?? ??────┘└More...──────────────────────────┘