[dm-devel] RE: How is the multipath pg policy group-by-nodena me any differen t than the failover policy?
goggin, edward
egoggin at emc.com
Tue May 3 16:11:56 UTC 2005
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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