HP OpenVMS Systems

fflush data?

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The Question is:

 
I am trying to write some file data to disk so that in
the event of power failure the file will contain all data
written to that file prior to the system crashing. The file
is created in DECC and is open for periodic writing for
24 hours and then closed. I have tried the C call fflush()
and I have tried NO BUFFER with setvbuf() but in each case
the file is empty upon resumption of system power. This file
receives over 100,000 writes per day and I would prefer not
to open/close it at each write.
 
TIA
 
Gordon
 
 

The Answer is :

 
    fflush will intruct the C RTL to move the data from the RTL
    buffers into the RMS buffers. To tell RMS to move its buffers
    out to disk, you should use the fsync functions (which will
    in the end call SYS$FLUSH).
 
    If the file indeed received 100,000s write per day, then the
    data must have been written through to disk (default buffer
    size is 8KB). The 'only' missing part will have been an updated
    end of file pointer. For desperate case, one can manually set
    this EOF pointer and magically bring the stored data to life!
    Check out DUMP/HEAD/BLOCK=COUNT=0 and $SET FILE/ATTR=(EBK=x,FFB=y)
 
    hth,
    	Hein.
 

  

     

     
answer written or last revised on ( 21-APR-1998 )
     
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