Date: Sun, 30 Sep 2001 21:16:26 +0100 From: ian j hart <ianjhart@ntlworld.com> To: Ian Dowse <iedowse@maths.tcd.ie> Cc: Cy Schubert - ITSD Open Systems Group <Cy.Schubert@uumail.gov.bc.ca>, Mike Harding <mvh@ix.netcom.com>, admin@rshb.com.ru, stable@FreeBSD.ORG Subject: Re: dirpref gives massive performance boost Message-ID: <3BB77D9A.77B56F56@ntlworld.com> References: <200109301852.aa80614@salmon.maths.tcd.ie>
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Ian Dowse wrote: > > In message <200109301651.f8UGpFs02421@cwsys.cwsent.com>, Cy Schubert - ITSD Ope > n Systems Group writes: > >In message <20010930162030.10A5B133C1@netcom1.netcom.com>, Mike Harding > >writes: > >> So it sounds like there would be some benefit in tar'ing and untarring > >> /usr/local, /usr/ports, /usr/src, etc. which will be less > >> disruptive... > > > >At work, I don't have the luxury of doing a wholesale conversion as all > >the machines have one disk and most have only one partition. I've been > >toying with the idea of duplicating up /bin for example to /bin.new, > > It is on directory hierarchies such as /usr/ports and /usr/src > where there are a large number of "associated" directories that > the biggest performance improvements are to be made. This is > especially true when the hierarchy takes up only a small proportion > of the whole partition. > > Before the dirpref changes, files were generally allocated physically > close to their parent directory, but directories were spread out > randomly across the filesystem. The dirpref changes make it much > more likely for directories to be located close to their parent > directory too. For /usr/ports, this is a huge win - before these > changes, a port's main directory and its 'files' subdirectory were > located on average a third of the filesystem size away from each > other (I think). Now they are likely to be just a few blocks away, > maybe even waiting in the disk's cache. > > Since these improvements are all about the placing of subdirectories, > there isn't much point in re-creating flat directories such as > /bin, /usr/bin etc. For /usr/local, it might only be worthwhile > re-creating some application directories that have a huge number > of subdirectories. However, a system with a large number of user > home directories might see a big improvement if /home was rebuilt, > because all of a user's files would end up much closer together > on the disk. > > Ian > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-stable" in the body of the message Any effect on vinum? FWIW I have 4 disk raid10 /usr and /var -- ian j hart To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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