On Mon, Apr 15, 2013 at 11:30:54AM +0200, Erwin Geerdink wrote:
> Hi,
>
> After reading the man pages for fdisk, disklabel and the FAQ, I created
> a FFS2 filesystem on my 1TB usb harddisk (which I want to use for
> backups). The disk contains an OpenBSD MBR partition which spans
> the entire disk. I issued the following commands:
>
> # fdisk -i sd0
> # disklabel -E sd0
> (created partition 'a' covering the whole OpenBSD part)
> # newfs -O 2 sd0a
>
> This works fine, however only 931GB of the disk is allocated, while
> originally it was capable of storing 1000GB (FAT filesystem).
> Since an additional 5% is reserved for root, df -h tells me there is
> just 878GB available.
>
> Where has the remaining diskspace gone?
Into the marketing departement's manager bonus.
Disk size as sold and reported by some OS is in 10 based units.
OpenBSD uses 2 based unit.
Your disk has 1953525168 sectors, which translates into 1000204886016 bytres.
1000204886016 / 1024 / 1024 / 1024 = 931.
Using 10 bases gigs, you'll get about 1000G.
-Otto
>
>
> # fdisk sd0
>
> Disk: sd0 geometry: 121601/255/63 [1953525168 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: A6 0 1 2 - 121600 254 63 [ 64: 1953520001 ] OpenBSD
>
>
> # disklabel sd0
>
> # /dev/rsd0c:
> type: SCSI
> disk: SCSI disk
> label: Bell Carbon
> duid: bd112d36e9fc8c1f
> flags:
> bytes/sector: 512
> sectors/track: 63
> tracks/cylinder: 255
> sectors/cylinder: 16065
> cylinders: 121601
> total sectors: 1953525168
> boundstart: 64
> boundend: 1953520065
> drivedata: 0
>
> 16 partitions:
> # size offset fstype [fsize bsize cpg]
> a: 1953525056 64 4.2BSD 8192 65536 1
> c: 1953525168 0 unused
>
> # df -h
> Filesystem Size Used Avail Capacity Mounted on
> /dev/sd0a 924G 199G 679G 23% /mnt/sd0a
>
>
> Best,
> Erwin
