Re: Help in debugging ACF connection issue

["Hu, Yong via Tech-talk" <tech-talk at aps.anl.gov>]

Hi Érico,

Thanks for sharing this interesting subtle CA connection issue. 

Another thing worthy of checking: If you use systemd, make both IOC services start after network-online.target, to avoid your IOCs start before your NICs/IPs are fully functional.

I always think CA clients will continuously attempt to connect until timeout (EPICS_CA_MAX_SEARCH_PERIOD, 300-second). I am surprised it never connects in your asCa case.

Cheers,

Yong

From: Tech-talk <tech-talk-bounces at aps.anl.gov> on behalf of Érico Nogueira Rolim via Tech-talk <tech-talk at aps.anl.gov>
Date: Tuesday, February 24, 2026 at 1:14 PM

On 2/24/26 07:02, Michael Davidsaver wrote:

On 2/23/26 3:36 PM, Érico Nogueira Rolim via Tech-talk wrote:

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

So it never connects at all?  Odd.

Indeed. We rarely need to write to these PVs, so we can go without noticing these issues for months, and it doesn't connect for that whole time.

...
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?

This seems an interesting test.  The asCa code [1] creates a separate CA client context to what the dbCa code (aka. CA_LINK) uses [2].  Both should use the same configuration from the environment, and so should yield the same result.

https ://github.com/epics-base/epics-base/blob/3855356d2faef8ccf67ae5d0a368d44ef2527a5c/modules/database/src/ioc/as/asCa.c#L172-L173

https ://github.com/epics-base/epics-base/blob/3855356d2faef8ccf67ae5d0a368d44ef2527a5c/modules/database/src/ioc/db/dbCa.c#L1108-L1109

I will make a patch for this and deploy it when possible, then. I'll report back when I have results!