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Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!news.mira.net.au!news.mel.connect.com.au!munnari.OZ.AU!spool.mu.edu!howland.reston.ans.net!Germany.EU.net!zib-berlin.de!irz401!uriah.heep!news From: j@uriah.heep.sax.de (J Wunsch) Newsgroups: comp.unix.bsd.freebsd.misc Subject: Re: Hard drive configuration during install Date: 31 May 1996 17:41:36 GMT Organization: Private BSD site, Dresden Lines: 49 Message-ID: <4onb0g$df@uriah.heep.sax.de> References: <31B5EB5A.60BA@www.play-hookey.com> Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch) NNTP-Posting-Host: localhost.heep.sax.de Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Newsreader: knews 0.9.6 X-Phone: +49-351-2012 669 X-PGP-Fingerprint: DC 47 E6 E4 FF A6 E9 8F 93 21 E0 7D F9 12 D6 4E Ken Bigelow <kbigelow@www.play-hookey.com> wrote: > When following this process on a pair of 2 GB drives however, I noticed > that the automatic assumptions left 1008 blocks unassigned. Looking > further, I found the assumed geometry to be 973 cyl x 64 hd x 63 sec. The > physical geometry is 3893 x 16 x 63. Neither of both is likely the physical geometry; both are ``translated''. Physical geometries are largely irrelevant these days, and for all but very few drives, you can't even express them in a simple C * H * S formula. There are things called ``zone bit recording'' (or whatever your disk vendor calls it), so the actual number of sectors per track varies across the disk surface. SCSI disks often do report the actual values for the number of heads and the number of cylinders: uriah # scsi -f /dev/rsd0.ctl -m 4 | fgrep Number Number of Cylinders: 2493 Number of Heads: 5 uriah # scsi -f /dev/rsd1.ctl -m 4 | fgrep Number Number of Cylinders: 3992 Number of Heads: 9 Anyway, this is mostly a ``FYI'' item only, nothing you would really care for. (As you can see in the example above, the number of 16 heads you've been quoting as ``physical'' is likely to be wrong. It's questionable whether so many surfaces would even fit into a slim 3.5" disk, and the actual number of data heads is usually odd since one of the surfaces is used for servo purposes.) > I always install from the DOS partition, and it works fine. Can anyone > tell me why it works when I use the wrong disk geometry, but not when I > insert the actual geometry? And can I do something to change this? The only important geometry figure is the one the BIOS uses. FreeBSD _must_ be setup to use the same, otherwise your BIOS won't find the partition when it comes to booting. That's why you saw the `F?' -- the boot selector detected a partition entry in the fdisk table that was not pointing to a valid boot block. -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE Never trust an operating system you don't have sources for. ;-)