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Re: 19990719: LDM Linux problem

Gilbert,

Thanks for your comments.  Now forward them to the Linux folks to have
their mmap problem fixed.  The Linux limitations is not an LDM problem,
it's a Linux problem.  There has been extensive testing at UCAR about this
problem and the solution is to buy more memory.  I'ts only about a $1 an
megabyte.  The general solution is to have minimum  amount of RAM equal
about 125% of the LDM queue.  Even then, the Linux bug starts appearing
when the queue grows larger then 750 megabtyes.  Just stating the facts.

Robb...

On Mon, 19 Jul 1999, Unidata Support wrote:

> 
> ------- Forwarded Message
> 
> >To: General Support <address@hidden>
> >From: Gilbert Sebenste <address@hidden>
> >Subject: To Robb Kambic: LDM Linux problem
> >Organization: .
> >Keywords: 199907191431.IAA16008
> 
> Hello,
> 
> I assume this message needs to go to Robb Kambic, but here goes!
> 
> I am having a problem running LDM under Linux. It is more of an
> inconvenience than anything, but it is a serious one, and I believe
> someone has come up with a solution that I'd like you to implement.
> 
> As far as I can tell, if I make my LDM queues very large, especially
> larger than the amount of memory that my system has, it causes it to hang,
> crash, or, in the case of shutting down and starting the LDM, it can cause
> the machine to practically lock up for 20 minutes. I have just figured out
> why: my beloved Linux has this glitch where it will literally store all
> the data coming off the LDM until the RAM is full.
> 
> I have heard that David W. down at UIUC in Champaign has found a solution
> to the bug. Could you PLEASE add this bugfix, or whatever works, so that
> the LDM dumps the data right into the disk instead of storing it in
> memory?
> 
> By the way, outside of this bug, which is fairly significant, I will
> never, EVER use any flavor of Unix again besides Linux, so long as I have 
> any say in it. It's stability, even with the problem noted above, is
> worlds better than any other OS I've ever used. Frankly, I'd rather scrape
> the back of my thighs with a cheese grater and then go on a plane ride
> with the Kennedys rather than using Solaris ever again. That was
> version 6; I've been told 7 is an entirely different and nasty ball
> of whacks. Anyway, if it hasn't been said emphatically enough, thank you,
> THANK you for supporting Linux versions of UNIDATA software!!!!
> 
> Please let me know the status of this. I am using Linux 5.2. on
> weather.admin.niu.edu (primary) and weather3.admin.niu.edu (backup).
> BTW, all my downstream sites have access to both machines now.
> 
> Gilbert
> 
> *******************************************************************************
> Gilbert Sebenste                                                     ********
> Internet: address@hidden    (My opinions only!)                     ******
> Staff Meteorologist, Northern Illinois University                      ****
> Work phone: 815-753-5492                                                ***
> *******************************************************************************
>  
> 
> 
> ------- End of Forwarded Message
> 

===============================================================================
Robb Kambic                                Unidata Program Center
Software Engineer III                      Univ. Corp for Atmospheric Research
address@hidden             WWW: http://www.unidata.ucar.edu/
===============================================================================