Help in debugging ACF connection issue

[Érico Nogueira Rolim via Tech-talk <tech-talk at aps.anl.gov>]

Hi, all!


We have had some occasional issues when rebooting servers in our BPM
infrastructure, and I'd like to request guidance on how to best debug it.


We have an IOC for each RF front-end and an IOC for the actual BPM
board, and we have an Access Security rule to block writes to certain
front-end PVs when the fast orbit distortion detection is enabled in the
BPM board. Sometimes, when these servers are rebooted, the front-end IOC
is unable to connect to the PV from the BPM board IOC (verified using
the ascar command), and (correctly) blocks writes to the relevant PVs.
If I restart the front-end IOC, it immediately connects to the board
IOC. The front-end IOC comes up faster than the board IOC, since it
doesn't require as much setup and has fewer records to process at
initialization.


I have already tried reproducing this outside of reboots, and waiting a
long time between starting the front-end IOC and the board IOC, but it
has always established a connection immediately. What could be causing
the issue we observe? These IOCs are running on the same server, though
our EPICS_CA_ADDR_LIST is empty because we rely on broadcasts for this
subnet.


While writing this email, I thought of adding a proxy record in the
front-end DB that connects to the outside PV, and checking the
connection on that. Should it yield different results? Is the connection
path considerably different between DB links and AS links?


Cheers,

Érico


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