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20030227:ASU-Unidata update
- Subject: 20030227:ASU-Unidata update
- Date: Thu, 27 Feb 2003 12:34:17 -0700 (MST)
Hi Nancy,
Yes, I will leave the allow on thelma until we resolve what we want to
do..not a problem.
However,
<snip>
I still don't quite understand why that outgoing message would be 4 times
the size of the incoming data stream,
<snip>
This makes no sense unless you are feeding other sites..Do you have any
allows in your ldmd.conf?
<snip>
Another curiousity that's poking up is that the number of data packets
being received by mothra exceeds the number sent by thelma. This is
resulting in a "Number of periods not equal" message at the LDM comparison
site.
<snip>
This is also quite strange...is mothra requesting anything else from
another site..i.e. NLDN from striker..?
Please send me your ldmd.conf file, I think that is the best way for me to
investigate...
I went to ASU for a year in 1993 to get some physics behind me before
going to grad school here at CU, and I know how ASU and U of A are like
oil and water..:) Just a comic aside to the issues at hand of getting
prompt data delivery from U of A.. Go Devils!
Cheers,
-Jeff
____________________________ _____________________
Jeff Weber address@hidden
Unidata Support PH:303-497-8676
COMET Case Study Library FX:303-497-8690
University Corp for Atmospheric Research 3300 Mitchell Ln
http://www.unidata.ucar.edu/staff/jweber Boulder,Co 80307-3000
________________________________________ ______________________
On Thu, 27 Feb 2003, Nancy Selover wrote:
> Jeff,
> Our system administrator has been monitoring the traffic into and
> out of mothra as he has been directing the Datacomm people to try and solve
> our network slowness issues, particularly with getting the LDM data. Here
> is his latest note. Is it possible to stay on thelma for a week to see if
> it is stable. Also, do you know why we are getting more products than
> thelma (per the upstream-downstream comparison website)? I would guess it
> is a function of what products we keep rather than what's in the queue.
>
> Thanks,
> Nancy
>
> Nancy J. Selover
> Asst. State Climatologist
> Office of Climatology tel: 480-965-0580
> Arizona State University fax: 480-965-1473
> Tempe, AZ 85287-1508 e-mail: address@hidden
>
> > -----Original Message-----
> > From: Talbot Brooks
> > Sent: Thursday, February 27, 2003 11:05 AM
> > To: Nancy Selover
> > Cc: Joseph Zehnder
> > Subject: RE: Unidata update
> >
> > Well, it looks like you're getting your all of your data now. It's still
> > a bit slow at times, but it looks like everything is coming through. Even
> > if mothra is sending a message back to thelma, I still don't quite
> > understand why that outgoing message would be 4 times the size of the
> > incoming data stream, but I'll roll with it. Another curiousity that's
> > poking up is that the number of data packets being received by mothra
> > exceeds the number sent by thelma. This is resulting in a "Number of
> > periods not equal" message at the LDM comparison site.
> >
> > Regardless, can you let things run from thelma for a week or two? If it
> > stays "up", then I think our culprit is definitely at UofA or the link
> > between here and there and not on the shoulders of our DataComm folks. If
> > this does prove to be the case, I think the path of least resistance would
> > be to leave our source as thelma and bag getting stuff from U of A - it's
> > gonna be a nightmare trying to get that fixed...
> >
> > Thanks,
> >
> > Talbot Brooks
> > ASU Dept. of Geography
> > 600 E Orange St.
> > Tempe, AZ 85287-0104
> >
> > (480) 965-7832
> > address@hidden
> >
> > -----Original Message-----
> > From: Nancy Selover
> > Sent: Thursday, February 27, 2003 10:00 AM
> > To: Talbot Brooks
> > Cc: Joseph Zehnder
> > Subject: RE: Unidata update
> >
> > Talbot,
> > LDM has to constantly send messages to thelma (or whatever data
> > server is upstream) requesting data. The upstream server responds to each
> > request with a data stream, which then ends, and mothra asks for another
> > one, etc. It's a continual series of processes that start and stop.
> > Hourly there is a statistical report mothra sends out to ucar on
> > latencies. As mothra gets the data in, it also starts and stops a series
> > of decoders which decode various data types, as soon as it detects that
> > they are in the queue.
> >
> > Nancy
> >
> > Nancy J. Selover
> > Asst. State Climatologist
> > Office of Climatology tel: 480-965-0580
> > Arizona State University fax: 480-965-1473
> > Tempe, AZ 85287-1508 e-mail: address@hidden
> >
> > -----Original Message-----
> > From: Talbot Brooks
> > Sent: Wednesday, February 26, 2003 5:16 PM
> > To: Joseph Zehnder; Nancy Selover
> > Subject: Unidata update
> >
> > Howdy -
> >
> > As of 5 pm, the discrepency report from Unidata between mothra and
> > thelma shows minimal data missing and latencies under 500 seconds. Using
> > eHealth to track network traffic to and from mothra shows a substantial
> > increase in data transmission. So, it looks like you've been getting most
> > of your product for at least the last 4-5 hours.
> >
> > However, there is something puzzling (at least to me) going on. The
> > percentage of bandwidth used inbound is running at about 4%. The
> > percentage of bandwidth outbound is as high as 18%. Any guess why there
> > would be more outbound than inbound traffic?
> >
> > My take/educated guess:
> >
> > This suggests some sort of large-scale read activity taking place on
> > the drive. If it were transmitting the results of that read back out, it
> > could potentially account for the high outbound network traffic. If this
> > is the case, I would single it out as the primary suspect for latencies as
> > high as 500 seconds - the drive in mothra is at best a 10,000 rpm disk
> > with a transfer rate around 9ms - the box is simply choking on rapid I/O.
> >
> > To kinda confirm, I went in and physically touched the box and
> > watched the green drive light flicker on and off rapidly. This drive is
> > in almost constant action. I can affirm that this trend is related to
> > LDM, since all traffic dropped to zero when Nancy had LDM stopped earlier
> > in the week.
> >
> > Thanks,
> >
> > Talbot Brooks
> > ASU Dept. of Geography
> > 600 E Orange St.
> > Tempe, AZ 85287-0104
> >
> > (480) 965-7832
> > address@hidden
> >
>