Hello, I to have noticed a 'slowing' affect. Naturally I dismissed fragmentation. Is this 'normal' and fixable?
On Wed, 2006-02-08 at 11:54 +0100, David Guerizec wrote: > Hello, > > Le Lundi 06 Février 2006 19:50, Duncan a écrit : > > Fragmentation doesn't tend to be as much of an issue on Linux, with "real" > > filesystems, as on MSWormOS, particularly FAT/FAT32. I'm running all > > reiserfs here, FWIW. It doesn't have a compaction tool (defrag, on > > MSWormOS), but I've not noticed any issues as a result. > > Fragmentation seems to be a myth for anyone on Linux, and I was enclined to > believe that myth until I started to use Gentoo. > > At first, a brand new gentoo system is fast, but after a few months and a > dozen emerge -uDN world, things tend to slow down to a point that is barely > acceptable. In fact, the first time I tought that maybe I installed too many > things, and that my system was crippled with cruft. > But then I had to repartition my hard drive, so I made a backup (tar zcvpf) > of > my different partitions, fdisk, mkfs, and tar zxvpf. > The system was exactly the same as before, just the partition size had > changed. > But then emerge -S was much faster than before the operation, as well as > common portage operations. > > Since then, I've tried to do the same on several servers, without the fdisk > operation, just tar cp, mkfs, tar xp, and I've always noticed an appreciable > speedup. > > The only explanation that comes from this experiment is fragmentation. > And I think Gentoo is more sensible to fragmentation than binary > distributions > because it has to deal with many small files, often changing, during > compilation and rsynchronisation. > > So the directories sensible to fragmentation are IMHO, /var/tmp > and /usr/portage, and they are the ones to put on different partitions. > > Now, I don't have exact numbers to prove my sayings, but anyone can make the > test themself, if they already have /var/tmp and/or /usr/portage on separate > partitions. > > I didn't have time yet to sort out what kind of filesystem is more or less > sensible to fragmentation, but from my experience, ext[23] is not a good > candidate for /var/tmp or /usr/postage. Reiser3 has proven to fragment too, > and one of the last system I installed was formated with XFS, which I will > "defragment" in a few weeks. Hopefully I could then come with numbers. > > BTW, does someone know of a tools to show the fragmentation level of a *nix > filesystem ? > > David > > > > -- Dr Gavin Seddon School of Pharmacy and Pharmaceutical Sciences University of Manchester Oxford Road, Manchester M13 9PL, U.K. -- gentoo-amd64@gentoo.org mailing list
