  Configuring cluster allocation classes? 
 The Question is:
 
We have a three node cluster consisting of  two GS140s and an 8400 running Open
 VMS 7.1-2. We have two storage works cabinet with 4 sets dual HSJ50
 controllers. The HSJ controllers are connected through a CI star coupler. We
 wish to install local drives i
nto the main CPU cabinet and make them available to the cluster.
 
Currently the ALLOCLASS sysgen parameter is set to 1 on all CPUs and
 Controllers. Are vender support is telling us to change the allocation class
 sysgen parameter on all three CPUs to make them unique. Another source of
 technical information tells me th
e CPUs will only see disk drives connected to  controllers that have the same
 allocation class as the CPU. Can you shed any light?
 
The local drives will be SCSI connected to a KFTIA integrated I/O Module. Does
 this require us to set the MSCP sysgen parameters to 1.
 
Thanks for all your help in the past.
Mike from Tallahassee
Senior System Programmer
 
 
 
 
 The Answer is:
 
  Your vendor telling you that you should consider changing the host
  allocation class on the host is correct, as duplicate unit numbers
  are forbidden within any disk or any tape allocation class.  On
  recent OpenVMS versions, a port allocation class can be used, and
  this mechanism provides rather better granularity than does the host
  allocation class.
 
  Your source of technical information, on the other hand, is incorrect.
  To serve through the devices from a storage controller to other cluster
  members, the OpenVMS system must typically be in the same allocation
  class as the storage controller.  Since you are not serving through the
  storage to other cluster members, this restriction does not apply.
 
