Re: fdisk chs numbers

On 2008-11-06 09:29:08 +0000, me@xxxxxxxxxxx (R) said:

I can't get my head around fdisk's CHS numbers.
I wonder if anyone here can help.

Here's my OS X boot disk:

sh-3.2# fdisk /dev/disk0
Disk: /dev/disk0 geometry: 38913/255/63 [625142448 sectors]
Signature: 0xAA55
Starting Ending
#: id cyl hd sec - cyl hd sec [ start - size]
-----------------------------------------------------------------------
1: EE 1023 254 63 - 1023 254 63 [ 1 - 409639] <Unkn[...]
2: AF 1023 254 63 - 1023 254 63 [ 409640 - 607911936] HFS+
3: 0B 1023 254 63 - 1023 254 63 [ 608583720 - 16296544] Win95[...]
4: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

There are 3 partions. The hidden EFI partition (1), OS X's HFS+
partition (2) and a FAT partition (3). What I don't get is, why
are the "Starting" and "Ending" CHS numbers all the same?

I had some fun formatting a Sun disk recently - disks with EFI labels are formatted quite differently from "normal" disks and it is possibly and likely that cylinders/heads/sectors simply aren't used at all on EFI disks.

AIUI a lot of disks lie about their geometry anyway.

The LBA numbers seem plausible.

They do.

Presumably "Win95" is a misnomer, as I can't imagine Windows 95 booting from EFI.

--
Chris

.

Relevant Pages

  • Re: How best to set up a separate /home partition, and pros/cons
    ... number of primary partitions. ... EFI also allows the newer GUID Partition Table partitioning ... Hackintosh - or using Mac disks - opens up the possibility of Apple ... GPT or something else; the only link is that only an EFI PC can ...
    (Ubuntu)
  • Re: fdisk chs numbers
    ... EFI disks. ... dummy MBR, but Apple use it as a real MBR for Boot Camp. ... I discovered that as soon as there is 1 active partition ...
    (uk.comp.sys.mac)
  • Re: mounting USB Sandisk
    ... early in the EFI boot sequence when the USB disks are attached (the ... system is a zx6000 with EFI 1.10). ... SCSI disks get discovered). ...
    (comp.os.vms)
  • Re: bugged sysinstall, bsdlabel, zfs, gmirror - recept for disaster :)
    ... So after a thirty minutes I had a plan, and my server had 4 disks ... gmirror - raidz environment. ... mount point for every partition in slice. ... offset to use (the end of the previous partition plus one, ...
    (freebsd-stable)
  • bugged sysinstall, bsdlabel, zfs, gmirror - recept for disaster :)
    ... Yesterday I've decided that's about time to test zfs functionality on my home server PC. ... A couple of weeks ago I bought new desktop PC, so I had a bunch of PATA disks from old one ... Problem with labels created with sysinstal, is that it aks for a mount point for every partition in slice. ... So I've added gmirror to loader.conf ...
    (freebsd-stable)