Date: Sat, 10 Oct 1998 15:37:25 +0930 From: Greg Lehey <grog@lemis.com> To: francisco@natserv.com, freebsd-fs@FreeBSD.ORG Subject: Re: Optimizing space utilization Message-ID: <19981010153725.T3369@freebie.lemis.com> In-Reply-To: <199810100424.AAA21260@federation.addy.com>; from Francisco Reyes on Sat, Oct 10, 1998 at 12:24:30AM -0000 References: <199810100424.AAA21260@federation.addy.com>
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On Saturday, 10 October 1998 at 0:24:30 -0000, Francisco Reyes wrote: > I am looking for certain info on the filesystem to try to maximize space > utilization. > > Any pointers/URLs would be appreciated. > > What I am trying to find out is: > > -- What is the smallest unit FreeBSD manages. Is this a block or fragment? A fragment. > From what I have seen FreeBSD creates blocks of size 8K by default. > > -- What is a fragment (man newfs has a "frag size") The smallest unit FreeBSD manages. > --What space does an inode entry takes? Currently, 260 bytes. > How many file entries go into each Inode? One. The inode *is* the file; the names are just links to the inode. > If I know how many files I have for a fs I am trying to see if space > could be saved by using less inodes. None. You need exactly one inode per file. > -- One of the options in newfs is to optimize for "space". Does it really > save space? What kind of degradation will be seen by using that flag > instead of "time" optimization?. The simple (and useless :-) answer is "Time optimization saves time; space optimization saves space". It's difficult to summarize the differences in a sentence or two. "The Design and Implementation of the 4.3BSD UNIX Operating System" goes into some detail about this. There's also McKusick's paper on UFS, which you'll find on the second CD-ROM in /usr/share/doc/smm/05.fastfs/. Greg -- See complete headers for address, home page and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
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