Difference of opinion about my disk geometry

[Doug Barton]

On 08/26/2010 11:02 PM, Bruce Cran wrote:
> CHS is totally obsolete, and can be ignored for anything but really old
> computers I think - LBA has been used since about 2000. If you use the
> modern partitioning tool in Windows, diskpart.exe, you don't get told
> about the geometry at all; if you use gpart in FreeBSD you get told
> about the fwheads and fwsectors but partitions are specified in terms
> of an offset.

Thanks to you and to Partha for the replies. I'd like to make it clear I 
am not arguing with either of you, I don't even know enough about disks 
to BE dangerous. :)  I am simply trying to understand what's going on 
(and make sure I'm not doing something now that's going to cause my data 
to go away tomorrow). In Linux fdisk I get errors that the partitions 
don't end on cylinder boundaries. In FreeBSD sysinstall when I 
re-installed my 9-current partition last night I got the following error 
after finishing the fdisk step, "chunk ad0s2 does not start on a track 
boundary" (ad0s2 is the extended partition I created in windows). So 
neither OS seems to like the current situation, but if you're telling me 
that those errors are harmless I have no problems ignoring them.

What I definitely think is true at this point is that my 25-year-old 
"knowledge" about this stuff is now worse than useless. :)  So I need to 
learn how to to do it better. I took a look at the man page for gpart 
and it's way over my head. I was not impressed with the way that the 
disk slicer for the ubuntu installer worked. Biggest single objection 
was that it considers 1 gigabyte to be 1,000,000 bytes, but at least it 
said this somewhere obvious so I could do the math to make it "right" 
myself, and fwiw Nautilus and the gnome "Disk Utility" seem to have the 
same view of the world, even though 'df -h' shows the "real" Gbs. 
However the results seemed Ok. I did some digging on line and saw many 
references to gparted, which is included in the ubuntu live cd, and 
seemed quite easy to work with.

So my current line of thinking is that when I get ready to redo this 
disk for the last time (which should be soon now that I have my grub 
situation sorted) that I'll boot the ubuntu live cd and slice the whole 
disk first with gparted, then install windows, the 2 FreeBSDs (and 
specify the 30401/255/63 geometry to sysinstall just in case), then 
Linux last so that it can install grub and I'll finally be done! If 
anyone sees a problem with that process I'd appreciate it if you let me 
know asap because at this point even I am tired of fiddling with this 
stuff. :)


Doug

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