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Date:      Sat, 2 Mar 2002 09:43:11 -0500
From:      Brian T.Schellenberger <bts@babbleon.org>
To:        David Smithson <david@customfilmeffects.com>
Cc:        freebsd-questions@FreeBSD.ORG
Subject:   Re: defragment UFS
Message-ID:  <20020302144311.A9387BA03@i8k.babbleon.org>
In-Reply-To: <3C807A58.1030209@customfilmeffects.com>
References:  <002301c1c1a6$b9e06f70$0801a8c0@ethel> <20020302050142.GB1634@raggedclown.net> <3C807A58.1030209@customfilmeffects.com>

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On Saturday 02 March 2002 02:08 am, David Smithson wrote:
> I see.  Well that's dandy.  I have another filesystem-related question.
>  I have a 1.2TB file server running FreeBSD.  The filesystem is exported
> via SMB.  When I view the properties of a SAMBA shared folder, there are
> two file sizes shown:  "size" and "size on disk".  The "size on disk" is
> consitently greater than the "size".  I ignorantly assumed this meant
> that data was fragmented.  Do you have any idea what this means?
>
> The question of data size came about when I ran a backup of a directory
> tree that is reportedly 76 GB.  The Large DTF tape medium I'm using is
> supposed to hold 108 GB at it's only compression ratio of 1:2.59.  I ran
> "tar -cvf /dev/sa0 /dir-tree".  After some time, tar reported that it
> had reached the end of the medium.  Clearly 76 GB should fit on this
> tape.  I can't figure out what is happening here.  Any ideas?

Just a guess, but if you have very, very many very small files, it could be 
the blocksize-rounding loss.   Thus if you have a file with 4 bytes of data, 
and a blocksize of 1k, then you have 1020 bytes of wasted space; or, a "size" 
of 4 and a "size on disk" of 1024.

>
> Thanks for your help.
>
> Cliff Sarginson wrote:
> >On Fri, Mar 01, 2002 at 08:57:16PM -0800, David Smithson wrote:
> >>Hi all.  Is there a defragment utility for FreeBSD?  Is it even
> >> necessary?  If not, why not?
> >
> >No.
> >No.
> >No matter what size file you have on FreeBSD it will never have more
> >than one partially filled block, when a file grows it fills the spaces
> >up rather than allocating new blocks uneccesarily a la DOS.
>
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-- 
Brian T. Schellenberger . . . . . . .   bts@wnt.sas.com (work)
Brian, the man from Babble-On . . . .   bts@babbleon.org (personal)
                                ME -->  http://www.babbleon.org
http://www.eff.org   <-- GOOD GUYS -->  http://www.programming-freedom.org 

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