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Date:      Tue, 27 Feb 1996 21:07:45 -0500 (EST)
From:      "Adrian T. Filipi-Martin" <atf3r@stretch.cs.virginia.edu>
To:        Peter Stubbs <peters@staidan.qld.edu.au>
Cc:        Peter van Heusden <pvh@leftside.its.uct.ac.za>, freebsd-fs@freebsd.org
Subject:   Re: Compressing filesystem for FreeBSD
Message-ID:  <Pine.SUN.3.90.960227210012.29395A-100000@stretch.cs.Virginia.edu>
In-Reply-To: <6BD18783D77@aidan.staidan.qld.edu.au>

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On Wed, 28 Feb 1996, Peter Stubbs wrote:

> On 24 Feb 96, Peter van Heusden wrote:
> 
> > 
> > Does anyone know if anyone has done any work on writing a
> > compressing filesystem for FreeBSD? I've been thinking about this,
> > and the strategies to do it, and I'd like to know if there is any
> > previous work out there I can refer to...
> > 
> This isn't much of an answer, but since nobody else has said 
> anything I'll point out that the the nearest thing that's here now is the 
> pseudo-device gzip which allows gziped a.outs to be run. Perhaps all 
> that is needed is to extend that device to other files?
> 
> I'd hate to see us go the same direction as MS-DOG and create a 
> single file with all the other files compressed into it. Perhaps the 
> netware 4 technique of compressing files that haven't been access for 
> a certain time using a (very) niced daemon?

	The real problem with compressing a file system that is often
forgotten is that you are increasing the cost in CPU cycles for a disk
I/O.  While I have had dos/linux enthusiasts go on about how compressing
your filesystem can both improve I/O bandwidth and increase available disk
space, the cost is often fogotten.  On a multi-user system, the CPU is not
idle during disk I/O.  I think there would also be problems with paging
and reads in general.  Which block of the disk contains the nth byte?  In
short, I don't see it being worth the effort. 

	Adrian
        System Administrator for the NVL, NIIMS and Telemedicine labs

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