Re: Search for disconnected channels

["Ernest L. Williams Jr." <ernesto@slac.stanford.edu>]

Chris Slominski wrote:
> We will eventually identify and fix the iocs, but since I am 
> archiving; I want to loose as little data as possible.
> I am doing now something similar to what you suggest, checking for 
> disconnected channels every so often. When there are some, I try to 
> open another connection to the same channel instead of deleting and 
> reconnecting.
> I posted to find a more elegant way than what I am doing now, since I 
> want to minimize the time I spend away from monitoring the active 
> connections.
I agree with Andrew's recommendation and that should be much faster to 
implement than the other solution.
If you indeed have multiple subnets/VLANS and a router, you will need to 
configure directed broadcasts.
This will allow the beacons to traverse the various VLANs to reach the 
CA clients. 
Basically, it is better to configure CA servers, CA clients, and network 
to handle the CA Beacons.


Cheers,
Ernest




> Andrew Johnson wrote:
> > Hi Chris,
> >
> > On 2012-02-23 Chris Slominski wrote:
> >   
> > > I was thinking of a local solution for one process on one host, but I
> > > will consider your global solution. I'm not sure I want every client
> > > restarting their searches for disconnected channels.
> > >     
> > I would look into trying to fix those IOCs so that they are configured with 
> > the right subnetmask, which (unless they're actually in a different IP subnet) 
> > is all you *should* have to do for their broadcasts to be seen.
> > Within the context of a single client you could just delete and then re-
> > connect and subscribe to any one of the disconnected channels, which won't 
> > affect the rest of the program since by definition the channel isn't live.  If 
> > there are no disconnected channels then there's obviously no need to do this, 
> > so the issue should be self-regulating.
> >   
> > > > On 23.02.2012 14:18, Chris Slominski wrote:
> > > >       
> > > > > I want to be able to force my EPICS channel access client to begin a
> > > > > new search for currently disconnected channels.We have small short
> > > > > term pc104 iocs come and go and sometimes they are  not configured
> > > > > correctly to broadcast when they have been booted up. A client
> > > > > listening to the channels won't see a beacon anomaly and  begin the
> > > > > channel search sequence.
> > > > >
> > > > > I can see a couple of ways to do this.
> > > > >
> > > > > - Send a network beacon to the CA Repeater.
> > > > > - Issue a search for some non-existent channel.
> > > > >
> > > > > Please advise on what is a good way to do this. Example code or
> > > > > references to EPICS source code are very welcome, as I am neither
> > > > > familiar with EPICS base software, nor am I an experienced network
> > > > > programmer. My client software uses EPICS 3.13.10.
> > > > >         
> > - Andrew
> >