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20050513: LDM - ldm tuning guides



>From: "Steve Wanzong" <address@hidden>
>Organization: SSEC
>Keywords: 200505132053.j4DKrwvw027908 LDM tuning

Hi Steve,

>Institution: UW-Madison/SSEC
>Package Version: 6.3.0
>Operating System: Red Hat Enterprise Linux WS release 3 (Taroon Update 4)
>Hardware Information: dual 2GHz XEON, 1.5Gb Ram, Singe scsi hard drive
>
>Inquiry: Hello,
>
>Are there any best practice guides for tuning the ldm process.

No, not really.  Configuring the LDM is discussed in the Basics
section of our LDM web pages, however:

http://www.unidata.ucar.edu/content/software/ldm

>We are
>starting to use the ldm products to feed an AWIPS system.  The majority
>of the products will need to be piped to either an executable or perl
>script.

OK, this should not be too much of a problem depending on the Perl
scripts involved.

>Even with the ldm ingesting only NIMAGE (every image) and run through
>zlibg2gini, the computer can get somewhat sluggish.

Our experience on a dual AMD 2400+ box running FreeBSD 4.10 is that
we can process _all_ of the data available in the IDD and the machine
is still very responsive.  Even though we are not uncompressing
the NIMAGE images using zlibg2gini at the moment, we used to process
all of those files and did not see any performance problems.

>This will only worsen as more products are requested.

I suspect something other than zlibg2gini.  Can you do some
troubleshooting to find out where the system is bogging down?  I
suggest using 'top' to see if the zlibg2gini processes are using too
much CPU and 'iostat' to see if the problem is related to disk I/O.
Please let us know what you find out.

The other thing to report are:

- size of your LDM queue
- amount of swap space available
- whether or not you are seeing any disk problems in /var/log/messages

Cheers,

Tom
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