From owner-freebsd-questions@FreeBSD.ORG Wed Dec 9 22:48:51 2009 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id B0EE71065670 for ; Wed, 9 Dec 2009 22:48:51 +0000 (UTC) (envelope-from freebsd@edvax.de) Received: from mx02.qsc.de (mx02.qsc.de [213.148.130.14]) by mx1.freebsd.org (Postfix) with ESMTP id 5957A8FC0C for ; Wed, 9 Dec 2009 22:48:51 +0000 (UTC) Received: from r55.edvax.de (port-92-195-228-22.dynamic.qsc.de [92.195.228.22]) by mx02.qsc.de (Postfix) with ESMTP id C639C1E1E8; Wed, 9 Dec 2009 23:48:49 +0100 (CET) Received: from r55.edvax.de (localhost [127.0.0.1]) by r55.edvax.de (8.14.2/8.14.2) with SMTP id nB9MmlKG001845; Wed, 9 Dec 2009 23:48:49 +0100 (CET) (envelope-from freebsd@edvax.de) Date: Wed, 9 Dec 2009 23:48:47 +0100 From: Polytropon To: James Phillips Message-Id: <20091209234847.042af7c0.freebsd@edvax.de> In-Reply-To: <675083.74248.qm@web65510.mail.ac4.yahoo.com> References: <20091209002231.EB7D01065741@hub.freebsd.org> <675083.74248.qm@web65510.mail.ac4.yahoo.com> Organization: EDVAX X-Mailer: Sylpheed 2.4.7 (GTK+ 2.12.1; i386-portbld-freebsd7.0) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: freebsd-questions@freebsd.org Subject: Re: Dangerously Dedicated (was: How do I create large ...) X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: Polytropon List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 09 Dec 2009 22:48:51 -0000 On Wed, 9 Dec 2009 11:42:31 -0800 (PST), James Phillips wrote: > I sort of followed the discussion as well. There was some > disagreement about what "dangreously dedicated" means. For comparison, I seem to remember that the two concepts are called "compatibility mode" and "(dangerously) dedicated mode", with the "dangerously" looking like a further addition. > Does it mean > getting rid of the DOS partition table (slices?) The use of slices - "DOS primary partitions" has often been suggested for FreeBSD, but it has always worked without them. I think the neccessarity to use them is what I said before: compatibility. FreeBSD can handle "no slices" well, but maybe other operating systems and "Windows" can't? A common problem is that due do compatibility (again), the number of slices is limited to 4. > Or, does it mean > creating a slice or disks without BSD partitions? How should this be possible? A partition (not a "DOS primary partition", to avoid misunderstandings) is required for creating a file system. Let's say you want to create a file system on a disk: # newfs da0 This means that a partition is created - da0c - and inside this partition the file system resides. This is a common method for accessing data disks (disks you don't boot from). > The Handbook (18.3) > says: "If the disk is going to be truly dedicated to FreeBSD, you > can use the dedicated mode. Otherwise, FreeBSD will have to live > within one of the PC BIOS partitions. FreeBSD calls the PC BIOS > partitions slices so as not to confuse them with traditional BSD > partitions." Exactly. No "dangerously" here. > The programer in charge of the change seemed to indicate that the > "Dangerously dedicated" mode (I assume that means no BSD partititons) > conflicts with "GEOM: Modular Disk Transformation Framework." No. It means "absence of a slice carrying the partitions", which is the dedicated approach. > GEOM > appears to be an asbtraction layer for accessing various disks. With > the move underway to start accessing all disk as SCSI(3 is device > independent (with translation help)) devices, it probably makes for > more elegant code. Handbook (19.2 GEOM Introduction) reads: > "GEOM permits access and control to classes -- Master Boot Records, > BSD labels, etc -- through the use of providers, or the special files > in /dev. Supporting various software RAID configurations, GEOM will > transparently provide access to the operating system and operating > system utilities." > The important thing in that quote is that "BSD labels" (and Master > Boot Records) are mentioned specificly. That's correct. BSD labels, usually created by disklabel, refer to FreeBSD partitions. MBR refers to slices (this is "DOS primary partitions", and maybe includes "logical volumes inside a DOS extended partition", all the things that produce "drive letters"). The only thing I can conclude from this is that the removal of dedicated mode is due to increasing compatibility with the abilities of GEOM... I've got lots of ? flying around my head... :-) Allow me to try a summary: Dedicated mode (also "dangerously dedicated mode"): da0 da0a da0b da0d da0e da0f da0g { (/) (swap) (/tmp) (/var) (/usr) (/home) } Compatibility mode: da0 da0s1 da0s1a da0s1b da0s1d da0s1e da0s1f da0s1g { [ (/) (swap) (/tmp) (/var) (/usr) (/home) ] } I'm not sure hgow this fits into the concept of installing multiple operating systems. For example, "Windows" requires you to install it in a slice. No problem with compatibility mode, but does this work in dedicated mode, too? I think the suggestion is "No, does not work" simply because the disk is DEDICATED to FreeBSD. -- Polytropon Magdeburg, Germany Happy FreeBSD user since 4.0 Andra moi ennepe, Mousa, ...