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From: kimcm@ambush.UUCP
Newsgroups: comp.sys.ibm.pc
Subject: Re: Re: UNIX more fragile than MS-DOS files?
Message-ID: <466@ambush.UUCP>
Date: Tue, 29-Sep-87 12:39:50 EDT
Article-I.D.: ambush.466
Posted: Tue Sep 29 12:39:50 1987
Date-Received: Sat, 3-Oct-87 12:07:25 EDT
References: <174@westmark.UUCP-> <1822@watcgl.waterloo.edu>
Organization: AmbraSoft A/S (Denmark)
Lines: 31

In article <1822@watcgl.waterloo.edu> smvorkoetter@watmum.waterloo.edu (Stefan M. Vorkoetter) writes:

>In the UNIX course I took, I was taught that the buffers get flushed
>every 30 seconds or so.  I guess this is by the daemon you mention
>below.

Actually it's not a daemon in the normal sense its part of the
kernel's job to flush the buffers. Normally the time between the
flushing is tuneable, which means that sites without source license
can modify the time interval.

In UNIX System V Release 3 the parameter to the kernel is called
NAUTOUP. 

NAUTOUP	  The NAUTOUP entry specifies the buffer age in seconds for
	  automatic file system updates. A system buffer is written to
	  the hard disk when it has been memory resident for the
	  interval specified by the NAUTOUP parameter. Specifying a
	  smaller limit increases system reliability by writing
	  buffers to disk more frequently and decreases performance.
	  Specifying a larger limit increases system performance at
	  the expence of reliability.
	  
BDFLUSHR  Specifies the rate in seconds for checking the need to write
	  the file system buffers to disk. The default is 1 second.
	
[AT&T 3B2 Computer UNIX System V Release 3 System Administrator's Guide]

The default time for updating buffers on the 3B2/600 is 10 seconds.

					Kim Chr. Madsen