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Path: euryale.cc.adfa.oz.au!newshost.carno.net.au!harbinger.cc.monash.edu.au!news.mel.connect.com.au!munnari.OZ.AU!news.ecn.uoknor.edu!news.ysu.edu!news.radio.cz!europa.clark.net!news.maxwell.syr.edu!nntprelay.mathworks.com!news.mathworks.com!fu-berlin.de!irz401!orion.sax.de!uriah.heep!news From: j@uriah.heep.sax.de (J Wunsch) Newsgroups: comp.unix.bsd.freebsd.misc Subject: Re: Sharing swap between FreeBSD and Linux, not enough partitions Date: 5 Jun 1997 21:34:46 GMT Organization: Private BSD site, Dresden Lines: 63 Message-ID: <5n7bdm$osi@uriah.heep.sax.de> References: <3392ED3D.E47@appliedreasoning.com> <01bc6f74$d1700440$f3e94dc2@hugo09.ticsoft.de> <5mv5nl$hdl@quail.swcp.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 Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:42498 crs@quail.swcp.com (Charlie Sorsby) wrote: (partitions vs. slices) > Or, one could say that SVR4's usage is somewhat confusing since BSD > predates SVR4... :) Not really. The term `partition' was a long-standing fact in Unix's tradition, of course. Up to SVR3.2, there wasn't much confusion about it, but you were usually also limited to a single fdisk entry for PC UNIX as well (with some vendor hacks to allow accessing the DOS portion of the disk). UNIX had partitions of its own. With SVR4, the PC UNIX variants apparently decided to throw away their old meaning of `partition', and take over this term for the fdisk table units. To differentiate, their sub-devices were called slices then. 386BSD 0.0 stood in the tradition of Unix, and didn't knew anything about fu***nny fdisk tables. It's got its partitions, of course. 386BSD 0.1 through FreeBSD 2.0 (i've lost the track on the other BSDs here) came with a hack that allowed sharing the disk with other systems using the fdisk table, but only allowing for one fdisk unit with BSD. Partitions were still the same. (The hack was to create another `magic' pseudo-partition, `d', covering the entire disk, while `c' covered the BSD portion.) This is comparable to SVR3.2 on PCs. With the advent of the slice code in FreeBSD 2.0.5, it's now been possible to handle the fdisk table appropriately. Bruce Evans, the architect of the slice code, decided to keep the term `partition' as it used to be, thus needed another term for the fdisk `super- partitions', and called them slices. It would perhaps have been better to choose a name that doesn't conflict with SVR4's usage, but that's too late now either. So, while BSD predates SVR4 (in principle), BSD != BSD, and the current usage of slices vs. partitions in FreeBSD has really been introduced after SVR4's precedent case. FreeBSD can still handle the sliceless case, standing in the Unix tradition. It owns the entire disk. Somehow, the term ``dangerously dedicated mode'' has been created to describe this kind of setup. The best you get by it is that you're largely independent of whatever `translation' your BIOS might use today. The only requirement for it to work is that this translation involves at least 15 sectors per track (the size of the primary and secondary bootstrap, which must be loaded initially using the BIOS). You can easily shuffle a disk around from an Adaptec to a NCR controller (or swap controllers, as i did recently), without ever thinking about the BIOS braindeadness again... Too bad, some BIOS vendors try to be `smart' these days, and don't boot a disk if they believe its master boot record contains an invalid fdisk table. :-((( HP's PCs are among this, even their more serious Netservers now. They should be shot for this braindamage. (It won't help a winluser with a broken disk very much, either.) -- 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. ;-)