Open FreddieAkeroyd opened 4 years ago
FreddieAkeroyd
commented
4 years ago The system clock on emma seems less stable than other instruments, regularly oscillating between 1 and 3 seconds out. Maybe this confuses the epics sync loop? While writing (17:00 4/10) the time difference has just reset back to OK.
ChrisM-S
commented
4 years ago Hi Freddie,
I’ve just checked my suspicion when I saw your last message. It’s because the Domain Time client has never been installed on EMMA – which means it is as stable as windows time on a VM - likely without updates from the host server enabled (that is about as stable as a jelly on a skateboard).
I’ll check it’s OK with them and push it out to them, I suspect it was never put on as the status of NDXEMM-A was was(/is?) a “just test machine” and also why it was not on Nagios. Of course, the invariable rule is that any “test” machine on a neutron beamline becomes a critical resource after some time ☺.
Chris
From: Freddie Akeroyd [mailto:notifications@github.com] Sent: 04 October 2020 17:17 To: ISISComputingGroup/IBEX Cc: Subscribed Subject: Re: [ISISComputingGroup/IBEX] EMMA-A: clock drift (#5773)
The system clock on emma seems less stable than other instruments, regularly oscillating between 1 and 3 seconds out. Maybe this confuses the epics sync loop? While writing (17:00 4/10) the time difference has just reset back to OK.
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The epics clock is drifting on emma-a, it started doing this around 14:00 on Saturday 3/10 and has lost 80 seconds in 24 hours. The system time looks fine, EPICS uses the windows high precision timer with periodic resyncs to system time. Looking at nagios record of inst etc time difference shows that the EPICS clock is less stable on emma than elsewhere, usually difference on instruments is always < 1s but on emma it has regularly got up to 7s before being reset and now is not being reset at all. Note has been sent to instrument scientist in case timestamps were being compared to external reference.
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