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20030508: LDM problems

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  • Subject: 20030508: LDM problems
  • Date: Thu, 08 May 2003 12:33:15 -0600
>From:  Joe Van Andel <address@hidden>
>Organization:  National Center for Atmospheric Research
>Keywords:  200305081646.h48Gk37U015345 LDM IDD reconnect

Hi Joe,

>we restarted our server - did it stop querying every 30 seconds?

We saw the 30 second reconnects stop at 23:27 UTC last night.  Is
this when the LDM was restarted?

Along the same lines, I just wanted to let you know of the availability
of our latest LDM implementation, LDM-6.0.10, which is much more
efficient in moving data than LDM-5.x.  I am eager to see if LDM-6
would go a long way toward addressing some issues you brought up with
the LDM last year:

  >Date:    Fri, 29 Mar 2002 14:49:24 -0700
  >From:    Joe Van Andel <address@hidden>
  >To:      address@hidden
  >cc:      address@hidden, Russ Rew <address@hidden>
  >Subject: LDM performance vs scp?
  >
  > This morning, I was benchmarking file transfers using LDM vs copying the
  > same file with 'scp'.  On the two files I checked, (1237KB and
  > 2446KB),LDM took 3 times as long to send the file compared to scp.
  >
  > Since I'm already short of bandwidth on my T-1 line, I'm quite concerned
  >that I can not afford to use LDM.
  >
  >Has anyone else benchmarked LDM to determine how fast it copies files,
  >vs alternatives (ftp, http, scp)?
  >
  >Any advice on how to improve LDM performance?
  >
  >--
  >Joe VanAndel
  >National Center for Atmospheric Research
  >http://www.atd.ucar.edu/~vanandel/
  >Internet: address@hidden

While the LDM-6 does not do on-the-fly-compression of products like
scp, it does use the available network resources a lot more efficiently
than LDM-5.  Constrained tests in long haul movement of data from UCAR
to Belem, Brazil demonstrated that LDM-6 was capable of moving over 8
times more data than LDM-5.  Admittedly, a large portion of the success
of this test was due to the long haul nature of the test itself, but US
sites that have upgraded to LDM-6 have commented to us that they have
seen a dramatic improvement in data reception (as measured by decreased
product latencies) after upgrading.

So, if you are game to upgrade to LDM-6, I would be happy to help.  In
addition, LDM-6 contains a routine that reports back real time
statistics on data reception that we need in order to monitor the
performance of the IDD.  We are asking sites to upgrade to LDM-6 in
order to provide us with this information.

Cheers,

Tom
--
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