Date: Mon, 10 Oct 2016 08:26:23 -0700 (PDT) From: "Rodney W. Grimes" <freebsd-rwg@pdx.rh.CN85.dnsmgr.net> To: Norbert Koch <nkoch@demig.de> Cc: freebsd-hackers@freebsd.org Subject: Re: Why at least 4 cylinder groups? Message-ID: <201610101526.u9AFQNuH091581@pdx.rh.CN85.dnsmgr.net> In-Reply-To: <b38d6452-fe18-aeb9-c176-f30fabd9b3f5@demig.de>
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> Hello. > > In an embedded system I am having a rather > small (static) ram disk of about 1.5MB, > formatted as UFS(1). > > Under FreeBSD 4 dumpfs shows me there is > 1 cylinder group. > > Under FreeBSD 9 and 10 I see 4 cylinder groups. > > 4 is hard coded as the minimum value in ufs/ffs/fs.h. Why? I beleive this constant only applies to UFS version 2, newfs -O 2, which is default in FreeBSD 9 and 10. > Is there any technical reason not to have less > than 4 cylinder groups? Probably on a UFS2 file system yes, but as far as I can see not on a UFS1 file system. > For my application the wasted 188KB make a difference. Try: newfs -O 1 > Thank you, > Norbert Koch -- Rod Grimes rgrimes@freebsd.org
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