Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!virtech!cpcahil
From: cpcahil@virtech.uucp (Conor P. Cahill)
Newsgroups: comp.unix.questions
Subject: Re: using fsck on mounted filesystem
Message-ID: <1989Nov28.010450.4118@virtech.uucp>
Date: 28 Nov 89 01:04:50 GMT
References: <21534@adm.BRL.MIL>
Organization: Virtual Technologies Inc.
Lines: 20

In article <21534@adm.BRL.MIL>, XDATMNLX%DDATHD21.BITNET@cunyvm.cuny.edu (Michael N. Lipp) writes:
> I know he shouldn't have used fsck on the mounted file system in the
> first place, but why did it work with microport-unix? I found out, that
> the number of missing blocks reported matches the free space reported by
> df. Interactive has the 'fast file system'. Could it be, that they write
> an empty free-block-list in the superblock of a file system when mounting
> it and keep the head of the free list in memory only? Thinking of a crash,

Interactive keeps the entire free list in memory and manipulates it there,
without manipulating it on the disk at all until the file system is unmounted.
That is why it takes so long to mount (and unmount) a file system under 386/ix.

Your guess that they invalidate the on-disk free list is correct.


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| Conor P. Cahill     uunet!virtech!cpcahil      	703-430-9247	!
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