The disk(8) program writes this information to the label area of a disk when it is initialized. The getdiskbyname(3) and getdiskbydev(3) routines may be used to read this information from the data base or disk label respectively.
The following list indicates the normal values stored for each disk entry.
Name Type Description
ty str Type of disk (e.g. removable_rw_optical)
ns num Number of sectors per track
nt num Number of tracks per cylinder
nc num Total number of cylinders on the disk
pa-h num Base sector number of partition [a-h]
sa-h num Size of partition [a-h] (sectors)
ba-h num Block size for partition [a-h] (bytes)
fa-h num Fragment size for partition [a-h] (bytes)
ca-h num Partition "cylinders-per-group" for newfs
da-h num Partition density ("bytes-per-inode") for newfs
ra-h num Partition "minfree" for newfs
oa-h str Partition optimization ("space" or "time") for newfs
ia-h bool Run newfs(8) on partition during initialization with disk(8)
ma-h str Partition mount point name
aa-h num Partition auto-mount on insert
ta-h str Partition file system type ("4.3BSD", "sound" etc.)
rm num Rotational speed in rpm (3600 default)
ss num Sector size in bytes
fp num Number of sectors in "front porch" of disk
bp num Number of sectors in "back porch" of disk
ng num Number of alternate groups on the disk
gs num Number of sectors per alternate group
ga num Number of alternate sectors per alternate group
ao num Sector offset of alternates in alternate group
os str Name of file to boot from
z0-1 num Locations (block number) of first level boot code
hn str Hostname
ro char Read only root partition (e.g. 'a')
rw char Read/write partition (e.g. 'b')