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Re: [dm-devel] RE: How is the multipath pg policy group-by-nodena me any differen t than the failover policy?



On Tue, 3 May 2005 13:22:32 +0100, Arthur Bergman wrote:
 
> Huh, as far as I understand it group_by_nodename uses the
> 
> /sys/class/fc_transport/target0:0:0/node_name information
> 
> from our setup, there are 8 paths to two controllers, there is no 
> failover cost but it defeats read caching pretty beadly to use both 
> controllers..
> 
> /sys/class/fc_transport/target0:0:0/node_name:0x50050768010003d5
> /sys/class/fc_transport/target0:0:1/node_name:0x5005076801000361
> /sys/class/fc_transport/target0:0:2/node_name:0x50050768010003d5
> /sys/class/fc_transport/target0:0:3/node_name:0x5005076801000361
> /sys/class/fc_transport/target1:0:0/node_name:0x5005076801000361
> /sys/class/fc_transport/target1:0:1/node_name:0x5005076801000361
> /sys/class/fc_transport/target1:0:2/node_name:0x50050768010003d5
> /sys/class/fc_transport/target1:0:3/node_name:0x50050768010003d5
> 
> 
> So all path that ends at a matching node_name, even if they are on 
> different transport targets get one path.

Right.  I mis-read the code in discovery.c.  Thanks.


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