Date: Fri, 25 Oct 2002 16:24:22 -0700 From: Terry Lambert <tlambert2@mindspring.com> To: Mark Valentine <mark@thuvia.demon.co.uk> Cc: Julian Elischer <julian@elischer.org>, Poul-Henning Kamp <phk@critter.freebsd.dk>, "M. Warner Losh" <imp@bsdimp.com>, freebsd-arch@freebsd.org Subject: Re: cvs commit: src/lib/libdisk Makefile chunk.c write_alpha_disk.c write_i386_disk.c write_pc98_disk.c Message-ID: <3DB9D2A6.5FBF0CE9@mindspring.com> References: <200210252215.g9PMFlBO083244@dotar.thuvia.org>
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Mark Valentine wrote: > > I fail to see how using ad0a makes it play better with other systems. > > Because DOS doesn't refer to its partition by its index in the MBR partition > table, and apparently some tools therefore feel free to reorder the table on > a whim. > > /dev/ad0a results in a method of locating the partition which is closer to > the DOS algorithm, and therefore survives this. > > /dev/ad0s1a makes an incorrect assumption about the MBR partition table index > being fixed, and therefore blows up. OK, say we buy this. How does the DOS algorithm distiguisch between partitions, if not by the order in the table? Specifically, if I have two partitions that are identical in all ways, other than a date stamp on one file way down in the FS on the partition, and one is "D" and the other is "E", other than the partition table order, how does it get the "D" and "E" assigend to the correspondingly correct devices? Does it key off the date stamp? > > If you are going to repartition your disk, then fix the fstab before you > > reboot for goodness' sake! It's not so complicated! > > I'm not repartitioning in any way which should affect FreeBSD. > > It doesn't sound complicated in this scenario, but when you consider > the partition table index embedded in backups and in scripts, it's > another matter. What you are saying is that you have some magic way to distinguish partitions. What I actually think you mean is that the partition table entries are reordered, and you want them to be distinguished gy the partition type IS (e.g. "165"), even though there are possibly multiple entries with identical partition type IDs. So the way that you are quietly and carefully not disclosing is to use something that isn't sufficiently unique. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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