Re: [ldm-users] NEXRAD2 Latency/Fragmented Data?

On Mon, 30 Jul 2012, daryl herzmann wrote:


On Mon, 30 Jul 2012, Gilbert Sebenste wrote:

 Interesting. Sorry it has taken me so long to respond, but
 I am gettign the feeds right on time. Blair, have you tried
 something like this in your ldmd.conf:

 exec    "/home/ldm/bin/pqact -f NEXRAD2 -p BZIP2/K[A-D]
 exec    "/home/ldm/bin/pqact -f NEXRAD2 -p BZIP2/K[E-K]
 exec    "/home/ldm/bin/pqact -f NEXRAD2 -p BZIP2/K[L-R]
 exec    "/home/ldm/bin/pqact -f NEXRAD2 -p BZIP2/K[S-Z]
 exec    "/home/ldm/bin/pqact -f NEXRAD2 -p BZIP2/T[A-Z]
 exec    "/home/ldm/bin/pqact -f NEXRAD2 -p BZIP2/P[A-Z]

Steve Emmerson kindly informed me that this is not quite the proper thing to do. Each pqact process should have an unique filename associated with it for when it writes state information to disk. The files can be simple sym links and it will 'trick' LDM just fine. So the recommendation is to simply:

cd /home/ldm/etc
ln -s pqact.gempak_craft pqact.gempak_craft.1
ln -s pqact.gempak_craft pqact.gempak_craft.2
ln -s pqact.gempak_craft pqact.gempak_craft.3

Then in ldmd.conf

exec "/home/ldm/bin/pqact -f NEXRAD2 -p BZIP2/P[A-Z] /home/ldm/etc/pqact.gempak_craft.1"

Also note with the above, that you would be missing the radars starting with D,N, and R :) Here's what I use:

exec    "pqact -p BZIP2/K[A-D] -f CRAFT /home/ldm/etc/pqact.CRAFT"
exec    "pqact -p BZIP2/K[E-H] -f CRAFT /home/ldm/etc/pqact.CRAFT2"
exec    "pqact -p BZIP2/K[I-K] -f CRAFT /home/ldm/etc/pqact.CRAFT3"
exec    "pqact -p BZIP2/K[L-O] -f CRAFT /home/ldm/etc/pqact.CRAFT4"
exec    "pqact -p BZIP2/K[P-R] -f CRAFT /home/ldm/etc/pqact.CRAFT5"
exec    "pqact -p BZIP2/K[S-Z] -f CRAFT /home/ldm/etc/pqact.CRAFT6"
exec    "pqact -p BZIP2/[A-J] -f CRAFT /home/ldm/etc/pqact.CRAFT7"
exec    "pqact -p BZIP2/[L-Z] -f CRAFT /home/ldm/etc/pqact.CRAFT8"

The 2-8 files are sym links back to the mothership.

I haven't seen any load average changes/improvements since I've done this...but that's just me, I guess. (shrug)


Gilbert Sebenste                                                    ********
(My opinions only!)                                                  ******
Staff Meteorologist, Northern Illinois University                      ****
E-mail: sebenste@xxxxxxxxxxxxxxxxxxxxx                                  ***
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