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[LDM #GUQ-669331]: Both Radar and Satellite feeds stopped downloading abruptly

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  • Subject: [LDM #GUQ-669331]: Both Radar and Satellite feeds stopped downloading abruptly
  • Date: Wed, 28 Aug 2019 10:54:20 -0600
John,

> Steve,
> 
> What we see when this happens is;
> 
> 1. We first notice that either the images for radar or the satellite (or 
> both) stop updating on our website.
> 
> 2. Secondly, we noticed that the output of "ldmadmin watch" stops entirely 
> except for our own outbound feed.  Normally, we see the inbound ldm/388 from 
> ucar servers for radar/satellite constantly updating with this command.
> 
> 3. Interestingly, the following command shows what appears to be normal 
> inbound ldm traffic from ucar (like lots of TCP traffic)
> tshark tcp port 388
> 
> 4. Nothing of note, as you mentioned, in the logs

Interesting.

I suspect that the NEXRAD3 and NIMAGE products are arriving, but that their 
latency (the time from when the product was created to when it arrives) is 
greater than the maximum latency parameter in the LDM registry -- in which case 
the receiving LDM process will simply discard them.

It would have been helpful if your LDM had been reporting statistics back to us 
as it would have made verifying this hypothesis very easy.

In order to manually verify this hypothesis, would you please monitor the 
latencies of arriving NEXRAD3 products via the command "notifyme -vl- -f 
NEXRAD3". For example

~: notifyme -vl- -f NEXRAD3 
20190828T163435.756731Z notifyme[25279]             notifyme.c:main:363         
        NOTE  Starting Up: localhost: 20190828163435.756444 TS_ENDT {{NEXRAD3, 
".*"}}
20190828T163435.756799Z notifyme[25279]             ldm5_clnt.c:forn5:460       
        NOTE  LDM-5 desired product-class: 20190828163435.756444 TS_ENDT 
{{NEXRAD3, ".*"}}
20190828T163435.757312Z notifyme[25279]             error.c:err_log:236         
        INFO  Resolving localhost to 127.0.0.1 took 0.00043 seconds
20190828T163435.759915Z notifyme[25279]             ldm5_clnt.c:forn_signon:294 
        NOTE  NOTIFYME(localhost): OK
20190828T163436.762442Z notifyme[25279]             
notifyme.c:notifymeprog_5:212       INFO         443 20190828163436.164060 
NEXRAD3 35910887  SDUS73 KDDC 281625 /pNETDDC
...

The above product had a latency of about 0.6 seconds ("20190828T163436.762442Z" 
minus "20190828163436.164060").

If the product latency gets larger than the maximum latency parameter 
(typically 1 hour), then you won't receive them.

Regards,
Steve Emmerson

Ticket Details
===================
Ticket ID: GUQ-669331
Department: Support LDM
Priority: Normal
Status: Closed
===================
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