Jason McIntyre wrote: > On Fri, Dec 16, 2005 at 01:50:48PM -0800, J.C. Roberts wrote: >> >> (2) When doing the installation disklabel, the "suggested" starting >> offset for the 'a' partition is 0? I know using an offset of 0 is >> discouraged on i386 and other systems (default is 63), so I figured I'd >> ask if using a 0 offset is the "best/correct" way for alpha? >> > > i'm going to let nick answer this (you're reading, right nick? ;) > *i* don't know, but i'd like to know the answer.
what made you guess? :) > faq 14.10 says, at one point: "Notice that the offset starts at 63. This > is what you want." *CHOKE* don't say things to me like that when I'm eating! > i'm trying to find where we document *why* 63 is "what you want" and if > it's MI. oh. my. gawd. That is so wrong. Disklabel offsets are very much machine dependent. On i386, that statement is STILL wrong, though you will be digging up either some unusual historic hardware or some really unusual devices for there to be an issue. Still, that's just wrong. On i386, it is NOT "63 sectors", it is "one (logical) track". On modern (>500M) hard disks, one logical track is 63 sectors, but that was not always the case, and I don't think it has to be the case now for "small" storage devices. The i386 systems have a "master boot record" (MBR) which occupies the very first sector on the disk. Custom is to have OSs starting on track boundaries, so you leave a one track offset. On i386, you can't have a zero sector offset, at least if you want to stay sane in the long run. Other platforms are different. Many need no offset, they don't use the "two layer" partitioning system that IBM AT descended machines use. This is a section I've been avoiding looking at, because I know it needs to be improved. Obviously, I underestimated HOW much it needs to be improved. Well, I guess I know how I'll be spending my Friday night... (once I get the lasagna out of the keyboard) Nick.
