HP OpenVMS Systems

Cluster Path Selection?

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The Question is:

 
Another article described some aspects of
SCS communications.
 
Please describe the way VMS chooses a comm.
path when multiple paths are available.
Does it have a priority list?  Does the
presence of (or possibility of) paths to other
nodes affect the way a path is chosen to a
particular node?
 
Of particular interest are: 10Mbit and 100Mbit
Ethernet, DSSI, and Fiber Channel.  We are
putting together a cluster of VAX/4105s,
Alpha 1000A and DS20s, where the only common
path is a 10Mbit Ethernet.  Will the cluster
use the faster paths where available, or
default to the least common demoninator?
 
Thank you.
 
 

The Answer is :

 
  The OpenVMS Cluster follows rules similar to rush hour commuters -- the
  best path is chosen, and the commuter then generally stays with that path
  until something requires consideration of a change.
 
  With an OpenVMS Cluster, the general rule is that non-emulated ports (CI,
  DSSI) are prefered over emulated ports (all PEDRIVER-based port devices
  including Ethernet and FDDI), and direct paths are prefered over served
  paths, and uncongested paths are prefered over congested paths.
 
  In your particular case, you will likely want to configure multi-host SCSI
  among the available Alpha systems -- direct paths are prefered over served
  paths.
 
  At:
 
    http://www.openvms.digital.com:8000
 
  please see:
 
    /72final/6318/6318pro_006.html#index_x_293
    /72final/4477/4477pro_034.html#index_x_1460
    /72final/4477/4477pro_034.html#index_x_1473
 

  

     

     
answer written or last revised on ( 13-MAY-1999 )
     
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