Date: 28 Jul 2005 15:07:12 -0400 From: Lowell Gilbert <freebsd-questions-local@be-well.ilk.org> To: Bob Johnson <bob89@eng.ufl.edu> Cc: Victor Semionov <victor@vmpbg.com>, freebsd-questions@freebsd.org Subject: Re: defragmentation in FreeBSD 4.11 Message-ID: <44ll3qu4v3.fsf@be-well.ilk.org> In-Reply-To: <200507281157.42688.bob89@eng.ufl.edu> References: <200507281157.42688.bob89@eng.ufl.edu>
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Bob Johnson <bob89@eng.ufl.edu> writes: > Message: 6 > Date: Thu, 28 Jul 2005 11:20:31 +0300 > From: Victor Semionov <victor@vmpbg.com> > Subject: Re: defragmentation in FreeBSD 4.11 > To: freebsd-questions@freebsd.org > Message-ID: <200507281120.31564.victor@vmpbg.com> > Content-Type: text/plain; charset="windows-1251" > > > > > This is one of the things I find really hard to get Windows users to > > > understand. They just won't believe that a company like Microsoft would > > > still be using a filesystem that needs defragmenting if it were possible > > > to design one that didn't. I often wonder why myself - after all, they > > > must have put a fair amount of work into NTFS, which at least doesn't > > > seem to get corrupted in a power failure. Did they make a trade-off I > > > don't understand, or is it just incompetence - or worse, a deal with > > > disk manufacturers to sell more disk? > > > > Microsoft used to claim that NTFS doesn't need defragmentation. Compared to > MSDOSFS, that's a reasonably accurate statement, but if you push it hard > enough, it will still become fragmented. > > > Why is it unnecessary to defragment UFS? > > > > In normal use, files never become fragmented enough to affect performance. In > a (loose) sense, files are intentionally fragmented in a controlled way so > that fragmentation doesn't cause problems. If you run fsck on a partition, > you will typically see fragmentation levels of less than one percent. Careful, there; "fragmentation" on a UFS is measuring a completely different thing than the same term applied to a Microsoft filesystem. For UFS, it refers to non-contiguous free blocks (fragments, actually), as opposed to the Microsoft terminology, where it refers to non-contiguous blocks within the same file. Everything you are saying is correct, but it will confuse people who don't realize the difference.
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