Path: utzoo!utgpu!watmath!watdragon!trillium!hjespersen
From: hjespersen@trillium.waterloo.edu (Hans Jespersen)
Newsgroups: comp.sys.att
Subject: Re: 6386 shutdown: I CAN'T BELIEVE at&t was really this stupid!
Message-ID: <14506@watdragon.waterloo.edu>
Date: 15 Jun 89 16:57:23 GMT
References: <483@oglvee.UUCP> <14401@bfmny0.UUCP>
Sender: daemon@watdragon.waterloo.edu
Reply-To: hjespersen@trillium.waterloo.edu (Hans Jespersen)
Organization: U. of Waterloo, Ontario
Lines: 28

In article <14401@bfmny0.UUCP> tneff@bfmny0.UUCP (Tom Neff) writes:
 
>To minimize the risk from power hits and crashes, I add a root cron job
>that performs a 'sync ; sync' every 10 minutes.  I have not been reliably
                  ^^^^^^^^^^^  

Why do people always do this? Running sync twice does nothing that
running sync once wouldn't do. Remember that 'sync' does NOT guarantee
that all delayed writes are actually written out to disk. It mearly
guarantees that they are in the queue to be written as soon as possible.
When you are at a shell prompt running

# sync
# sync
# sync

usually guarantees enough time has passed (since the first sync) that
the files were written to disk. Running

# sync;sync;sync

is kind of stupid since the first sync is not performed until after
you have typed the whole line in. 

-- 
Hans Jespersen
hjespersen@trillium.waterloo.edu
uunet!watmath!trillium!hjespersen