Date: Mon, 26 Aug 2002 18:04:42 -0400 From: Chris Ptacek <cptacek@sitaranetworks.com> To: "'Giorgos Keramidas'" <keramida@ceid.upatras.gr>, Chris Ptacek <cptacek@sitaranetworks.com> Cc: "'David Schultz'" <dschultz@uclink.Berkeley.EDU>, Carlos Carnero <zopewiz@yahoo.com>, freebsd-questions@FreeBSD.ORG Subject: RE: optimization changed from TIME to SPACE ?! Message-ID: <31269226357BD211979E00A0C9866DAB02BB998C@rios.sitaranetworks.com>
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OK, I am still trying to get a testbed setup to reproduce the issue. Once I do I am going to try setting the block size to 4096 and the fragment size to 512 (1:8 ratio) and minsize to 10%. To do this I believe I just: umount partition newfs -b 4096 -f 512 -m 10 /dev/wd0s1e Is this correct, or do I need to go through and delete and relabel, etc? - Chris > -----Original Message----- > From: Giorgos Keramidas [mailto:keramida@ceid.upatras.gr] > Sent: Monday, August 26, 2002 2:00 PM > To: Chris Ptacek > Cc: 'David Schultz'; Carlos Carnero; freebsd-questions@FreeBSD.ORG > Subject: Re: optimization changed from TIME to SPACE ?! > > > On 2002-08-26 15:02 +0000, Chris Ptacek wrote: > > I had a few questions... What actually causes the fragmentation to > > occur? I have tried just copying a small file over and over and > > this results in no fragmentation. This leads me to believe that the > > fragmentation is a result of simultainious open files or at least > > different file sizes. > > The way that the FreeBSD filesystem organises data on disk. This > "fragmentation" is not the same as fragmentation on a DOS partition, > if this is what had you confused. > > > Also it seems that when we switch to SPACE optimizaiton is based on > > the % fragmentation based on the minfree setting. Can I change the > > minfree for the filesystem (I have a dedicated cache partition) to > > like 27% (8 is default) so that I am much less likely to hit the > > SPACE case? > > Then the SPACE optimization will start when 3 times more space is > taken by fragments. But this is going to reserve 27% of the disk > space for the superuser and block allocation routines. This is too > much disk space to reserve :/ > > A better solution is probably to format the partition with a fragment > size equal to the block size as someone mentioned. I haven't tried > this though and I can't say how much it affects performance and why. > > -- > FreeBSD: The Power to Serve <> http://www.FreeBSD.org > FreeBSD 5.0-CURRENT #0: Wed Aug 21 22:08:19 EEST 2002 > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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