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Re: HA problem

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  • Subject: Re: HA problem
  • Date: Fri, 21 Nov 2003 16:10:29 -0700
Hi Youngsun,

My apologies for the delay in responding to you.  I was struck down by
the flu, but am better now.

The LDM can't provide lossless data transmission unless the downstream
node that reconnects is the same as the downstream node that
disconnected.  This is because the downstream node knows what it last
received, and that's the information it sends to the upstream node so
that the upstream node will know what to send next. 

I assume you've already thought of this, but you could just have your
upstream node send to both downstream nodes.  Yes, that would take twice
the bandwidth.  Is that your concern, or are there other reasons you're
trying to structure the downstream site this way?

Anne



> Youngsun Jung wrote:
> 
> Hi Anne,
> 
> How have you been?
> I found LDM is very stable and we can rely on LDM.
> I am testing it by distributing small dataset to 38 Weather Stations.
> It works pretty well.
> Now I am facing another problem..
> We operate 2 main servers. One is a main server and the other is a
> backup.
> Those 2 servers have their own IP respectively.
> But they also share one more IP for HA(High Availability) software.
> The problem is that LDM is not working for HA IP.
> 
> For example,
> ds1 : 152.1.87.45         ==> HA IP : 152.1.87.44
> ds2 : 152.1.87.46         ==> HA IP : 152.1.87.44
> 
> If system failure happens on ds1, ds2 takes over ds1's job.
> But still data transferring will not be bothered because host still
> sends data to 152.1.87.44
> even though ds2 receives data from the host physically.
> Is there a way to make LDM support HA IP?
> 
> And one more, will you have LDM workshop next year, too?
> Then I will try to send someone (or myself) to that workshop.
> 
> Great thanks for all your help.
> 
> Youngsun

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Anne Wilson                     UCAR Unidata Program            
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