Date: Thu, 01 Mar 2007 23:56:30 +0100 From: Ivan Voras <ivoras@fer.hr> To: freebsd-questions@freebsd.org Subject: Re: defrag Message-ID: <es7ln0$jff$1@sea.gmane.org> In-Reply-To: <44r6s8y4o5.fsf@be-well.ilk.org> References: <539c60b90703010849x33dd4bbbt8f6ca6aa0c8e83a0@mail.gmail.com> <es7gv6$3is$1@sea.gmane.org> <20070301165055.638b0a06.wmoran@collaborativefusion.com> <es7im6$9tu$1@sea.gmane.org> <44r6s8y4o5.fsf@be-well.ilk.org>
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This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig8915B63AE6E6CAA5EB45A56A Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Lowell Gilbert wrote: > If you know the standard computer science terminology, it can be > described quite tersely. UFS fragmentation is a way of avoiding > internal fragmentation from wasting too much space. MS-DOS-FS > fragmentation is an example of external fragmentation in the storage > space. They don't really have anything to do with each other. It looks like I actually AM arguing about semantics here: "UFS fragmentation" refers to dividing blocks (e.g. 16KB in size) into block fragments (e.g. 2KB in size) that can be allocated separately in special circumstances (which all boil down to: at the end of files). This is done to lessen the effect of internal fragmentation. "Fragmentation" without "UFS" prefix, as mostly used today (and which I believe it's how the original poster understands it) refers to dividing files into non-continuous regions, i.e. external fragmentation. Correct so far? "% fragmentation" message from fsck cannot refer to internal fragmentation as the numbers don't add up, so it almost certainly refers to external fragmentation. As I understand it from technical documentation, it is correct that UFS deliberately does external fragmentation of large files in order to make file allocation faster and more managable, except in "optimized for space" mode, correct? (the default being "optimized for time"). --------------enig8915B63AE6E6CAA5EB45A56A Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.4 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFF51oeldnAQVacBcgRAhTAAKDIAL//DkUy2ANBwJ9mwQ5VD79NKQCgka2Z qHYw5/qfE+JiM62u69MI/qs= =UzmN -----END PGP SIGNATURE----- --------------enig8915B63AE6E6CAA5EB45A56A--
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