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Re: Odd fdisk output
Mike Ayers wrote:
> 16 partitions:
> # size offset fstype [fsize bsize cpg]
> a: 10497808 0 4.2BSD 1024 8192 16 # (Cyl. 0 - 10414*)
^^^^^
> b: 2097152 10497808 swap # (Cyl. 10414*- 12494)
> c: 156301488 0 unused 0 0 # (Cyl. 0 - 155060)
> # fdisk wd0
> Disk: wd0 geometry: 9729/255/63 [156296385 Sectors]
> Offset: 0 Signature: 0xAA55
> Starting Ending LBA Info:
> #: id C H S - C H S [ start: size ]
> ------------------------------------------------------------------------
> 0: 00 0 0 0 - 0 0 0 [ 0: 0 ] unused
> 1: 00 0 0 0 - 0 0 0 [ 0: 0 ] unused
> 2: 00 0 0 0 - 0 0 0 [ 0: 0 ] unused
> 3: 00 0 0 0 - 0 0 0 [ 0: 0 ] unused
> #
>
> This system boots and runs fine, but I don't understand why.
Me neither. I'd expect a system like this to choke and die a horrible
death, but I've seen it reported before. 8)
> My problem is
> with the zeroed partition table. Is this just a standard way to indicate a
> single partition disk, or is something funky going on here?
The partition table is in sector 1, track 0, head 0 of the disk.
(or is that Sector 0, track 1, head 0? Whatever. FIRST physical
block of the disk. 8)
HOWEVER, that is where your OpenBSD partition is starting, not at the
usual one track offset (on a modern drive, typically 63 a starting
sector of 63, not 0). Hence, you blew away the partition table.
I'd highly recommend fixing it, even if it appears to be working for
now -- upgrades could get interesting...It may also continue to work
forever. No promises, either way. Apparently, the Partition Boot
Loader also works as a Master Boot Record, as far as the system BIOS
is concerned.
Making a change with fdisk would render your machine unbootable, as
would anything else that expected a Master Boot Record.
BTW: "Fixing" will involve removing all data, repartitioning and
disklabeling, and reloading.
Nick.
--
http://www.holland-consulting.net