[ewg] OPENSM cONFIGURATION

[Hal Rosenstock]

On 4/11/2014 2:21 PM, Atul Yadav wrote:
> Dear Team,
> 
> We are trying to build Fat tree topology.
> The details are given below:
> Unmanaged switches 36 port  quantity 5
> As per the some blog we need to modify the opensm.conf file
> But we are unable to identify some parameter like:-
>  root_guid_file    ???????

Fat tree routing will try to autodetect the roots but this may not work and it is better to specify the root GUIDs. In your case, they are the GUIDs for switches A and B.

The root GUID file is then provided to OpenSM either via the conf file or command line parameters. The command line parameter is [-a |
       --root_guid_file <path to file>]

OpenSM man page says:

       -a, --root_guid_file <file name>
              Set the root nodes for the Up/Down or Fat-Tree routing algorithm
              to the guids provided in the given file (one to a line).

It also says:

       If the root guid file  is  not  provided  (?-a?  or  ?--root_guid_file?
       options),  the  topology has to be pure fat-tree that complies with the
       following rules:
         - Tree rank should be between two and eight (inclusively)
         - Switches of the same rank should have the same number
           of UP-going port groups*, unless they are root switches,
           in which case the shouldn?t have UP-going ports at all.
         - Switches of the same rank should have the same number
           of DOWN-going port groups, unless they are leaf switches.
         - Switches of the same rank should have the same number
           of ports in each UP-going port group.
         - Switches of the same rank should have the same number
           of ports in each DOWN-going port group.
         - All the CAs have to be at the same tree level (rank).

       If the root guid file is provided, the topology doesn?t have to be pure
       fat-tree, and it should only comply with the following rules:
         - Tree rank should be between two and eight (inclusively)
         - All the Compute Nodes** have to be at the same tree level (rank).
           Note that non-compute node CAs are allowed here to be at different
           tree ranks.

       *  ports that are connected to the same remote switch are referenced as
       port group.

       **  list  of  compute  nodes  (CNs)  can  be  specified  by   -u   or
       --cn_guid_file OpenSM options.

-- Hal

> 
> Need your input for this ?
> 
> 
> 
> 
> Thank You
> Atul Yadav
>           
> 
> 
> 
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