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Re: Topology Questions (fwd)


===============================================================================
Robb Kambic                                Unidata Program Center
Software Engineer III                      Univ. Corp for Atmospheric Research
address@hidden             WWW: http://www.unidata.ucar.edu/
===============================================================================

---------- Forwarded message ----------
Date: Wed, 15 Nov 2000 10:58:38 -0500 (EST)
From: Tom McDermott <address@hidden>
To: Jim Koermer <address@hidden>
Subject: Re: Topology Questions

Jim,

I'm probably not very qualified to answer your questions, but I'll give it
a try based on my own understanding.  I'm sure more knowledgeable people
can offer corrections.

On Tue, 14 Nov 2000, Jim Koermer wrote:

> It seems that lately everytime that I check the Unidata topology pages,
> usually after I am seeing data problems, I seem to see the same thing--
> ~+60 minute latencies on FOS, but only a few minutes on McIDAS.  Why is
> there such a large difference in latencies, since I'm getting data from
> the same upstream site (UIUC or UMICH - it doesn't seem to matter which
> one)?

You may be getting it from the same upstream site, but the top level sites
are getting it from different sources.  The top level site for MCIDAS is
at SSEC, whereas the toplevel site for WMO, motherlode, is at Unidata,
which in turn is fed by 3 ingesting hosts at unidata, weather underground
and SSEC.  Now the amount of data on the WMO feed is much greater than the
MCIDAS feed, and this can result in greater latencies, especially when the
gridded data is coming in (this is especially true on the days they
transmit the models twice).  The FOS is really NOAAPORT now, whereas I
believe MCIDAS is not part of NOAAPORT, so this could account for some of
the discrepancy.
 
One thing you don't mention is whether your upstream site is also showing
+60 minute latencies on FOS.  If not, the problem may be in the quality of
your network connection to your upstream host.  I suppose you could ask
Unidata for alternative upstream hosts if the problem persists.  This may
or may not help, depending on whether your network bandwidth is maxed out
our not.

> It also seems that a number of downstream sites are in the ~+60 minute
> on FOS, but much lower on McIDAS. I've noticed this many times
> recently.  At 2250Z, I still haven't received any hourly ob data for
> 22Z, yet I'm sure that if I check back in an hour, I'll see most of the
> obs eventually came in.  Why should the obs that come in small batches
> be so delayed, yet the much larger McIDAS areafiles are coming in fine?
> 

Generally most sites request the text data on IDS|DDPLUS over the same
connection as the HDS feed, so if there is a slowdown with HDS, IDS|DDPLUS
will be affected as well.

Tom
------------------------------------------------------------------------------
Tom McDermott                           Email: address@hidden
System Administrator                    Phone: (716) 395-5718
Earth Sciences Dept.                    Fax: (716) 395-2416
SUNY College at Brockport





> Something just doesn't seem right.
> 
>                       Jim  
> -- 
> James P. Koermer             E-Mail: address@hidden
> Professor of Meteorology     Office Phone: (603)535-2574
> Natural Science Department   Office Fax: (603)535-2723
> Plymouth State College       WWW: http://vortex.plymouth.edu/
> Plymouth, NH 03264
>