From: SMTP%"drd@hep.ph.soton.ac.uk" 25-AUG-1993 09:59:56.08
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Subj: VAXC RTL and RMS
From: denholm@sotona.phys.soton.ac.uk (David Denholm)
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Subject: VAXC RTL and RMS
Date: 19 Aug 1993 10:03:18 -0500
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Hi,
I'm afraid I fall into the 'loath it' camp when it comes to RMS.
I just want to write straight forward c programs, which will work
wherever I go, so I dont really want to get involved with RMS much.
Trouble is, doing a simple fopen(filename, "w") and writing to it
makes such a racket on my external disk drive. The light is on
continuously, and the head sounds like it is moving continuously.
Same goes for programs like gzip, gunzip, lzdcmp, etc.
setvbuf doesn't seem to help [notwithstanding the fact the _IOFBF is
not defined in my (gnu) stdio.h file - perhaps someone could confirm
that I should be using _IOLBF=1, _IOFBF=2 (but _IONBF is already 4 ???)]
In desperation I dug out my RMS manual and looked up 'Tuning a sequential file'
if I do
fopen(filename, "w", "mbc=16", "mbf=2", "rop=WBH")
then my room becomes a whole lot less noisy.
What are the default values for these RMS parameters, and why aren't
they something like these - ie, what do I lose by doing the above ?
By how much more could/should I increase mbc - I notice a value of 120
in my archive of this group.
Is there any reason why I shouldn't go and put these into gzip.c, etc ?
(except using rop=RAH for reads, of course)
Now I notice that SHOW RMS_DEFAULT gives a system multi-block count of
16 - why do I have to explicitly set it to 16 in the open command ?
What does the VAXC RTL know that I dont.
many thanks
david denholm
-------------
David Denholm uk/colourbook : D.R.Denholm@southampton.ac.uk
Physics dept. internet : denholm@sotona.phys.soton.ac.uk
University of Southampton Tel : (0703) 592104 (work)
Southampton SO9 5NH (0489) 583174 (home)