Date: Fri, 10 Jan 1997 13:32:43 -0700 (MST) From: Terry Lambert <terry@lambert.org> To: joerg_wunsch@uriah.heep.sax.de Cc: FreeBSD-current@freebsd.org Subject: Re: Adding Hard Drives - Prepping Message-ID: <199701102032.NAA20483@phaeton.artisoft.com> In-Reply-To: <Mutt.19970110093121.j@uriah.heep.sax.de> from "J Wunsch" at Jan 10, 97 09:31:21 am
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> > I happen to agree with Ken here. > > > > When will devfs be standard so we can implement physical to logical > > translation layers and make this whole problem go away? > > That's only one part of the story. You still have to understand the > difference between slices, partitions, filesystems, and mounting. Not if you realize that there is no representational difference between a DOS partition, an extended DOS partition, and a disklabel (BSD or otherwise). The same tool can handle them all, as long as the interface for subdomain management is abstracted to be the same ioctl() to a physical to logical translation layer for all types of devices. Slices and partitions and extended partitions and CCD agregations and plain raw disks are all the same types of objects. Filesystems are relevent only in terms of "formatting" them. All "formatting" should work on all terminal devices originating in a physical to logical device translation layer, so it's not necessary for the tool to know about that (DOS has a seperate "fdisk" and "format" and has withstood years of battering). Mounting is an antiquated idea; it is relevent only because the device format recognition is expected to be done by a human telling the computer about a device it should already know about, either on a command line, or in a file called /etc/fstab. This is an implementation detail (of a bad implementation, in this particular case). What *is* relevent is the concept of mapping a device resource into a file system hierarchy. This is, however, totally logically independent of most of the process called "mounting", which should instead be implemented on device arrival notification following a successful attach. A user should be able to mapp as device resource into an FS hierarchy with no knowledge of the device apart from "it currently exists" and "if it currently exists, I want it here". This works for removable media, such as CDROM's and floppies, as well as it does for PCMCIA FlashRAM cards and disk drives, or more esoteric resources, such as mapped network drives with a nomadic system (laptop) in docked and undocked states. A user does *not* (and *should not*) have to understand the difference between slices, partitions, filesystems, and mounting. It is an implementation error that the user currently has to care about these things. Regards, Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.
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