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From: wpaul@ctr.columbia.edu (Bill Paul) Newsgroups: comp.unix.bsd.freebsd.misc Subject: Re: Big EIDE disk, old IDE controller Date: 11 Jul 1997 14:27:22 GMT Organization: Columbia University Center for Telecommunications Research Lines: 44 Message-ID: <5q5fsb$3fi$1@sol.ctr.columbia.edu> References: <timleeED2x4G.7AB@netcom.com> NNTP-Posting-Host: startide.ctr.columbia.edu X-Newsreader: TIN [version 1.2 PL2] Path: euryale.cc.adfa.oz.au!newshost.carno.net.au!harbinger.cc.monash.edu.au!munnari.OZ.AU!news.Hawaii.Edu!news.lava.net!news.flex.com!news.pixi.com!news1.best.com!su-news-hub1.bbnplanet.com!cpk-news-hub1.bbnplanet.com!news.bbnplanet.com!howland.erols.net!sol.ctr.columbia.edu!startide.ctr.columbia.edu!wpaul Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:44282 Daring to challenge the will of the almighty Leviam00se, Timothy J. Lee (nobody@not.for.email) had the courage to say: : Are there any potential problems with using a big ( > 504MB ) : EIDE disk on an old IDE controller with FreeBSD? It should work fine; when the FreeBSD kernel loads, it should probe the disk and tell you how large it thinks it is. This should be the full disk capacity, regardless of that the BIOS thinks. One thing you may have to do if you share this disk with with other OSes is tell the partition editor in the FreeBSD installer to use a specific geometry; there's a small chance it may guess the geometry wrong. (If it does get the geometry wrong, you may get a 'Missing operating system error' when you boot. Note it is still possible to boot FreeBSD off your hard disk using the install floppy's boot block; just type wd(0,a)/kernel at the Boot: prompt.) The main thing to be concerned about is where you place the root filesystem (/). While the kernel's protected-mode controller driver doesn't care about how many cylinders the your disk has, your BIOS does, and the boot block uses the BIOS to load the kernel image into memory at boot time. Usually the BIOS can't read past the 1024th cylinder, so you _must_ make sure that your root filesystem lies entirely below the 1024th cylinder. And I mean all of it; don't make one giant filesystem that covers the whole disk and say "Well, it falls partly below the 1024th cylinder; that should be good enough." It's not good enough: if you install a new kernel image, you aren't guaranteed that it all the blocks allocated to it will fall within the first 1024 cylinders, _unless_ the root filesystem itself resides completely within them. That said, as long as you follow this rule with the root filesystem, you can lay out all your other filesystems any way you like. -Bill -- ============================================================================= -Bill Paul (212) 854-6020 | System Manager, Master of Unix-Fu Work: wpaul@ctr.columbia.edu | Center for Telecommunications Research Home: wpaul@skynet.ctr.columbia.edu | Columbia University, New York City ============================================================================= "Now, that's "Open" as used in the sentence "Open your wallet", right?" =============================================================================