Date: Tue, 27 Aug 2002 00:00:29 +0300 From: Giorgos Keramidas <keramida@ceid.upatras.gr> To: 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: <20020826210028.GB6243@hades.hell.gr> In-Reply-To: <31269226357BD211979E00A0C9866DAB02BB998B@rios.sitaranetworks.com> References: <31269226357BD211979E00A0C9866DAB02BB998B@rios.sitaranetworks.com>
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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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