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List:       linux-cluster
Subject:    Re: re[2]: HA and process migration
From:       Bruce Walker <bruce () kahuna ! cag ! cpqcorp ! net>
Date:       2001-07-19 23:19:17
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> Greg wrote:
> 
> Per the Linux SSI for clusters presentation, they are actively working
> on it.  
> (See object migration under ongoing.)
> 
>      http://bjbrew.org/cpq/ssic_linux/montreal/sld053.htm
> 
> But I should let Bruce Walker speak to that.

Socket migration is on our roadmap (and also on the Mosix roadmap,
I believe).  It won't be there this month when we get the first
developer release out.

> 
> As far as Compaq's TruCluster's, they may have the infrastructure to support 
> moving an open socket, but they don't yet have process migration, nor socket 
> migration available in their released product.  Process migration is in
> the roadmap.  I'm not sure about Socket migration.
> 
> What Compaq TruClusters does have is the following, and it may make future 
> socket migration easier:
> 
>     Given a cluster of several nodes  (max. of 8 for now).
>     They elect one of them to be the service IP director.  (They use HA 
> technology to make this reliable.)
>     All service IP traffic goes to the service IP director.
>     The director then forwards it across the interconnect to the
> appropriate 
> node.
>     For each open socket the director maintains a mapping to the node
> the 
> traffic goes to.
>     
>     The director also maintains a list of listeners on each node.  
>     Then when a SYNC comes in for a specific port, it distributes it round 
> robin fashion between the listening nodes.
> 
>     They have a separate director for each service IP and a separate
> election 
> process for each director.
> 
>     Another interesting aspect is that on outbound SYNCs, you have the
> choice 
> to either identify
>     yourself by your local nodes IP, or by a service IP.  I'm not sure
> if they 
> support this to make 
>     admin of external systems easier, or if their is some HA aspect to
> it, or 
> maybe it is to allow the 
>     future process/socket migration to work.
> 
> I ASSUME that much of the above is implemented in the kernel, and even
> in the 
> tcp/ip stack.

I agree that this kind of capability is very important to socket migration
and I think you characterized the capability well.  Very much the same
capability is in Compaq's NonStop Clusters for Unixware and much of
that has been ported to Linux and should be available as part of the
open SSI cluster project.  Unless my understanding is wrong, it is also
very similar to Linux Virtual Server capability.  Comments?

bruce walker - open SSI cluster project,  compaq computers
> 
> Greg Freemyer
> Internet Engineer
> Deployment and Integration Specialist
> The Norcross Group
> www.NorcrossGroup.com
> 
> 
> Linux-cluster: generic cluster infrastructure for Linux
> Archive:       http://mail.nl.linux.org/linux-cluster/


Linux-cluster: generic cluster infrastructure for Linux
Archive:       http://mail.nl.linux.org/linux-cluster/

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