20040723: LDM Decorder Problem

>From:  Sameka Cook <address@hidden>
>Organization:  Office of Internet Services
>Keywords:  200407231853.i6NIrsaW019058 LDM ldmadmin

Hi Sameka,

>My name is Sameka Cook, I am very new to the LDM application and linux 
>world.    I am hoping you can assist me with a problem I am experiencing 
>testing LDM.

I will certainly try.  By the way, the best place to send email for
support on any Unidata-supported packages is our general User Support
inbox, address@hidden.  This mailbox is read by more than
one person, so you will be a lot more likely to get a quick answer
to questions if you send your inquries there.

>I am getting the following message when I run this command 
>ldmadmin check:
>Running version number ldm_clnt.c:270:.
>LDM was restarted 1 time(s)
>Last LDM restart at Jul. 19 12:00:45
>
>Critical LDM problems that need immediate attention:
>
>Potential LDM Problems:
>Non-zero Status messages occurred 212 time(s)
>Last one at Jun 23 14:14:35
>
>Decoder LDM problems:
>
>Do you have any idea what this mean, any assist would be greatly 
>appreciated.

This is very interesting mainly since the 'check' option for 'ldmadmin'
is one that we rarely, if ever, use.  Given this, it doesn't get
exercised much, and because of that, we don't think that the messages
it sends out are really of much use.

Are you experiencing problems with your LDM (e.g., not getting the data
you think you should, data reception is showing high latencies, etc.)?

If you are just exercising options in order to learn more about the
LDM, I would suggest the following:

'notifyme' is a very handy LDM application that allows you to see what
data your LDM is receiving and/or what data the upstream LDM(s) you are
feeding from is(are) receiving.  Here are two examples, one that shows
the use of 'notifyme' acting on the local LDM, and the other contacting
an upstream LDM:

notifyme -vxl- -f ANY -o 3600

This will list the metadata (product headers) for all of the data that
your LDM has received in the past 3600 seconds.  When the listing gets
to the present time, it will show the headers for products as they are
received.

If your upstream feed site's name is atm.geo.nsf.gov, the following
'notifyme' invocation will show what it has received in the previous
3600 seconds:

notifyme -vxl- -f ANY -o 3600 -h atm.geo.nsf.gov

The specification of the upstream host can be either by fully
qualified host name or IP address.  You will get information
back from the upstream host _if_ it is configured to allow your
machine to request data from it.

Another useful LDM command is 'ldmping'.  'ldmping' will show
if there is an LDM running on the machine you specify:

ldmping atm.geo.nsf.gov

If it appears that you are not receiving data, then using a notifyme
will either galvanize that view or show that you are, in fact,
receiving data (many sites think they are not getting data when their
problem is that they are not correctly setup to process the data).

If your LDM is being setup to relay data to other LDMs, then looking
through the LDM log file will be of most help.  For instance, if
your operating system has 'less' installed (Linux and FreeBSD have
this utility by default), then you could us it to look through
the log file(s):

<logon as 'ldm'>
cd ~ldm
less logs/ldmd.log

If you don't have 'less', you can use 'more':

<logon as 'ldm'>
cd ~ldm
more logs/ldmd.log

By looking through the log messages and cross referencing them with
example log messages listed in LDM web documentation:

Unidata HomePage
http://www.unidata.ucar.edu/
  LDM
  http://my.unidata.ucar.edu/content/software/ldm/index.html
    Releases
    ldm-6.0.14
      http://my.unidata.ucar.edu/content/software/ldm/ldm-6.0.14/index.html

      Tutorials and Presentations
      LDM Basics
      
http://my.unidata.ucar.edu/content/software/ldm/ldm-6.0.14/basics/index.html

      The LDM Logfile
      Format and interpretation
      
http://my.unidata.ucar.edu/content/software/ldm/ldm-6.0.14/basics/logfile-format.html

The last page in the list describes the various messages you might
see in your LDM log file.  This is a much better resource for troubleshooting
LDM problems than 'ldmadmin check'.

Another resource you will want to work through is the materials used
for Unidata LDM training workshops:

LDM Tutorial
http://my.unidata.ucar.edu/content/software/ldm/ldm-6.0.14/tutorial/index.html

Please let me know if you are experiencing or think you are experiencing
problems, or if you are just trying to get a feeling for how the
LDM works.

Cheers,

Tom
--
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* Tom Yoksas                                             UCAR Unidata Program *
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