Re: [EXTERNAL] Does every DB record need to produce a PV?

[Mark Rivers via Tech-talk <tech-talk at aps.anl.gov>]

To provide another counter-example I just checked the IOC for a Dectris Eiger detector.  This is an IOC that just runs a single X-ray detector.  It has about 30 plugins that do things like statistics, regions-of-interest, file saving, etc.  The IOC has 7,700 records.  There are 4,900 PVs in the autosave file, which store the state of the IOC and are loaded each time the IOC is started.  There are thousands of similar areaDetector IOCs deployed around the world.  I have never heard a complaint that there were too many PVs to be manageable, because they are accessed from hierarchical displays that are logically organized with many common elements.

Mark

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From: Tech-talk <tech-talk-bounces at aps.anl.gov> on behalf of Ralph Lange via Tech-talk <tech-talk at aps.anl.gov>
Sent: Tuesday, February 17, 2026 12:48 PM
To: EPICS Tech Talk <tech-talk at aps.anl.gov>
Subject: Re: [EXTERNAL] Does every DB record need to produce a PV?

 

On Tue, 17 Feb 2026 at 18:59, Hartman, Steven via Tech-talk <tech-talk at aps.anl.gov> wrote:

What makes you think this is unmanageable? There are plenty of counter examples of existing facilities where this works.

To name the one I know best:

With ~10 of its ~170 systems delivered, ITER's system is above 1 million EPICS records.

More than 90% of contributions are in-kind, including their EPICS-driven control systems. After passing acceptance testing and integration, they're ours, with basically no support from original designers. 

This is manageable with a configuration database, a strictly enforced hierarchical naming convention and thorough integration procedures.

Cheers,
~Ralph