Date: Sat, 3 Mar 2007 15:19:26 +0100 (CET) From: Christian Baer <christian.baer@uni-dortmund.de> To: freebsd-questions@freebsd.org Subject: Re: defrag Message-ID: <esc05e$30u3$8@nermal.rz1.convenimus.net> References: <539c60b90703010849x33dd4bbbt8f6ca6aa0c8e83a0@mail.gmail.com> <es7gv6$3is$1@sea.gmane.org> <20070301165055.638b0a06.wmoran@collaborativefusion.com> <es7im6$9tu$1@sea.gmane.org> <20070301172157.8fc10842.wmoran@collaborativefusion.com>
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On Thu, 1 Mar 2007 17:21:57 -0500 Bill Moran wrote: > But this also makes it _easy_ for the filesystem to avoid causing the type > of fragmentation that _does_ degrade performance. For example, when the > first block is on track 10, then the next block is on track 20, then we're > back to track 10 again, then over to track 35 ... etc, etc Fragmentation *this* bad doesn't happen on MS systems either. Although the systems are much more in danger of creating a big mess on the drive, there is a certain method included to reduce this, like only allowing the track numbers to either rise or fall (possibly per file access) but not back and forth over the drive. I can remember experimenting on my Commodore 64 (can anyone remember that ol' thing?) and the floppy drive. I stored a file all over the disc, one sector per track. The idea was to find out how much time it actually took to load a file "fragmented" like this - and made a really cool loading sound as well, especially if you had a floppy speeder like dolphin DOS. :-) I wanted to actually cause the drive to go from track 1 to 40 and then back again while loading a single file. But that didn't work. So if I started on track a and I am now on track c, then jumping to track b (with a<b<c) resulted in an error from the drive. Mind you, this was not a load command that I programmed. It's just the way the file was allocated on the disc. A certain logic to how files are saved on discs (no matter if hard or floppy) has been around for a fair while. Regards Chris
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