HP OpenVMS Systems

Increasing VIOC cache size?

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The Question is:

 
Hi
I would like to raise the VMS Virtual I/O cache from the default 3200 kbyte.
 Which sysgen parameter controls this?
Will the usual modparams.dat/autogen do the trick.
best wishes
jens chr
 

The Answer is :

 
  On OpenVMS Alpha V6.1 and above, the Virtual I/O Cache size is controlled
  by the SYSGEN parameter VCC_MAXSIZE. Although there are other VCC parameters,
  all except VCC_MAXSIZE are reserved to Compaq and should not be changed.
  Set a value for VCC_MAXSIZE in MODPARAMS.DAT, as for any SYSGEN parameter,
  and execute AUTOGEN. The new cache size will be realised on the next reboot.
 
  Also note that the unit for VCC_MAXSIZE is in BLOCKS, while the SHOW MEM
  display shows units of kilobytes. Thus, the default value for VCC_MAXSIZE
  is 6400 yields a cache size of 3200 kilobytes.  Be careful in choosing
  values to make sure you select the right units -- the different units have
  been known to cause confusion.
 
  The maximum VIOC cache size is also limited by the available space in S0
  and S1 system space (traditional thirty-two bit system space).
 
  The SDA command CLUE MEMORY/LAYOUT can be of interest here.
 

  

     

     
answer written or last revised on ( 29-JUN-2000 )
     
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