[evla-sw-discuss] NTP, EVLA MIB's and phase jumps

[James Robnett]

Short answer, we should retry timing tests after 11 or so.

james
-------------------------------------
   The symptoms reported this morning involving phase jumps
point squarely at the multicast NTP time signals from amos
and andy.

  Not only are the symptoms consistent with the phase jumps
the evidence that it started on Wednesday points directly
at the OS upgrades on amos and andy.

  I looked at NTP on both amos and andy and there is what
appears to be a problem.

  Both servers point at the stratum-1 GPS clock at the site
and a stratum-1 system in Green Bank.  They also point
at each other as peers to try and limit variance when one
or the other is rebooted.

  After the upgrade they also pointed at a 3rd peer running
the same hardware/OS to further limit jitter on reboots.

  Sadly that systems clock appears to be complete crap.
It seems to be 100ms off the others and is pulling amos/andy
backwards.  I've removed references to that system and
restarted NTP.

  In about an hour they should be settled enough to retry
timing tests on the EVLA.

  On a side note,  was the behavior seen consistent with some
boards syncing to the trailing 19.2 peak or can you only see
number of peaks off and not direction ?

james