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CI Performance: CIXCD vs CIPCA?

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The Question is:

Our ALPHA only CI-Clusters get 30MB/Sec thruput per star coupler, but our
mixed ALPHA and VAX CI-Cluster Star Coupler starts getting disk queues
after about 8MB/Sec.
Is this performance problem caused by the CIXCD's on the VAX?
If not were do we look?

The Answer is :

  The CI is rated at 70 megabits per second dual channel.
  Some CI controllers can use both CI channels in parallel, and
  some cannot.  CIXCD and CIPCA can use both channels.
  Performance of the XMI-based CIXCD and the PCI-based CIPCA is
  expected to be roughly equivilent for mamy workloads.  There are
  various workloads where CIPCA -- particularly when combined with
  HSJ-series storage controllers -- can do significantly better
  than CIXCD.
  Without rather more details on the configuration, the OpenVMS
  Wizard is not in a position to predict the particular problem
  presented.  Please contact the Compaq Customer Support Center
  for assistance in monitoring and tuning the configuration.
  (Values such as the kilobytes mapped rate will be of interest,
  as will the particular hardware configuration(s) and firmware
  versions involved.)

answer written or last revised on ( 20-JUL-2000 )

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