In message <[EMAIL PROTECTED]>, [EMAIL PROTECTED] writes: >Mike, I'll pay back your effort in replying to this long thing by >working up a patch for the "disklabel" manpage (at least) and, if you >want, I'll CC you so you can veto things you don't like. I do worry
At the risk of adding to the confusion, here is a less wordy description of the various disk layouts. The term `dangerously dedicated' seems to be used to refer to either options (B) or (C), so I will avoid using that term: (A) Normal sliced disk (assuming sectors/track = 63) sector 0: boot0 and the DOS slice table sectors 1..62: unused <start of slice 1> <start of 'a' partition> sector 63: boot1 sector 64: disklabel sectors 65-78: boot2 sectors 79-92: 'a' partition filesystem superblock Note that the disklabel, which contains a list of the partitions within a slice is actually contained within the space allocated to the first partition. To ensure that this does not get clobbered by the filesystem, the first 8k of every ffs filesystem is reserved for boot code and the disklabel. (B) Dedicated format created by sysinstall <start of slice 1> <start of 'a' partition> sector 0: boot1 and the DOS slice table, where the slice table contains one slice (slice 1) covering the entire disk, including sector 0. sector 1: disklabel sector 2-15: boot2 sectors 16-31: 'a' partition filesystem superblock In this case, there is no boot0, and boot1 serves as the boot loader that is invoked by the BIOS. Here, all of the boot code is contained within the first slice and also within the first partition. Again, the 8k reserved at the start of every ffs filesystem protects the boot code. Sysinstall sets up fstab to refer to the partitions as e.g. /dev/ad0s1a (I think). (C) Dedicated format using dummy slice <start of slice 4> <start of 'a' partition> sector 0: boot1 and the DOS slice table. The slice table contains a single entry (slice 4) that starts at sector 0 and has a size of 50000 sectors, whatever the real disk size is. sector 1: disklabel sector 2-15: boot2 sectors 16-31: 'a' partition filesystem superblock This is like (B) except that slice 4 instead of slice 1 is used, and the size of the slice in the slice table is bogus. The partitions on such a disk are usually accessed using the compatibility slice names such as /dev/ad0a. Ian To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-questions" in the body of the message