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[Support #AXO-576049]: LDM latency

Robert,

> I was wondering if you could give us a starting point to help diagnose a
> latency problem with LDM.  For the last few days, starting at 00Z, we
> are seeing delays in the delivery of NEXRAD2 data. It actually backs up
> about 1.5 hours before mysteriously catching back up to itself a few
> hours later. As it catches up, we see a spike on our MTRG graphs. (See
> attached).

How do you know that delivery is delayed?  What, exactly, are the
symptoms?

If you put the downstream LDM process that's receiving the NEXRAD2
data-products into verbose logging mode by sending it a USR2 signal,
then it will log the metadata of every arriving data-product.  You
can then compare the timestamp of the log message with the data-product
creation-time in the message to determine the latency.

Alternatively, you can use the "notifyme" utility or the command
"ldmadmin watch -f NEXRAD2" to do approximately the same thing.

> Do you have any idea what may be causing this? We're using LDM version 6.1.0

It's always best to use the most recent version of the LDM (which
is now 6.6.5).  You might try upgrading to see if the problem
dissapears.

> Any guidance you can provide would be greatly appreciate.
> 
> Thank you in advance.
> 
> R. Parsons
> Program Manager
> WeatherTAP.com
> 
> /Problem starts at 0z, catches up by 0430. See green part of graph./


Regards,
Steve Emmerson

Ticket Details
===================
Ticket ID: AXO-576049
Department: Support LDM
Priority: Normal
Status: Closed