Date: Sun, 3 Mar 2002 09:07:14 -0500 (EST) From: Paul Mather <paul@gromit.dlib.vt.edu> To: C J Michaels <cjm2@earthling.net> Cc: questions@freebsd.org Subject: RE: defragment UFS Message-ID: <20020303085739.J83257-100000@mule.Chelsea-Ct.Org> In-Reply-To: <CDEJIONOMGKHCNHBALKPAEKKCAAA.cjm2@earthling.net>
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On Sun, 3 Mar 2002, C J Michaels wrote:
=> > From: Paul Mather
=> > Sent: Saturday, March 02, 2002 8:00 PM
=> > Subject: Re: defragment UFS
[...]
=> > It's not really fiction. The smallest unit of disk space the end part
=> > of a file can occupy in a FFS filesystem is a fragment. Usually this is
=> > 1/8th the block size, and in 4.5, the default block size is 16 KB and
=> > default fragment size 2 KB. So, for example, the date of a 16385 byte
=> > file in such a file system would actually take up an extra 2047 bytes
=> > "on disk" compared to the reported file size.
=>
=> I didn't mean to imply the concept of slack space/fragmentation was fiction.
=> What I'm saying is that the numbers being reported by windows was fiction.
=> I'm not sure whether Windows or Samba is at fault, but the "size on disk"
=> calculations are way off the mark. I guess I should have clarified that.
I'm sorry, I did misunderstand what you were saying. Thanks for
clarifying.
=> > Anyway, that is why the "size on disk" will *always* be >= the "size"
=> > for any given file.
Aside from some confusing typos above (it should be the "data," not
"date" of a 16385 byte file:), I did make one important incorrect
statement, I realise. Files with holes *can* violate the above axiom.
(But, for "normal" files, it holds true.) :-)
Cheers,
Paul.
e-mail: paul@gromit.dlib.vt.edu
"Without music to decorate it, time is just a bunch of boring production
deadlines or dates by which bills must be paid."
--- Frank Vincent Zappa
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