Updated: April 19, 2023

Provide a common access method for hard disks


driver ... disk disk_options ... &

Runs on:

QNX Neutrino


One of the devb-* drivers.

The disk options control the driver's interface to If specified, they must follow the disk keyword:

Allow I/O writes of at most wr sectors and reads of at most rd sectors. If you specify path_id, target, and lun, this option applies only to the specified device; otherwise it applies only to the first device. The default is 4096 sectors.
Specify the device prefix:
  • disk name=usb names the devices /dev/usb0, /dev/usb1, and so on
  • disk name=usb@2:0:0 names the device at path 2, target 0, LUN 0 as /dev/usb0 (in the absence of any existing naming conflicts). Other devices use the default hd prefix.
  • disk name=usb@2 starts at /dev/usb2, /dev/usb3, and so on (in the absence of any existing naming conflicts)
Specify device numbers only on a closed system where you know all the devices and indexes.

The default is hd.

Don't use the geometry from BIOS int 13. By default, if you don't specify the translation option, the BIOS geometry is used.
Don't use the geometry from the partition table. The geometry from the partition table is used if you specify the nobios option, or the BIOS geometry is invalid.
Specify whether or not the device on the given path, target, and LUN is removable.
Set the maximum number of command retries on the specified path, target, and LUN. The default is 10.
Set the rw and group command timeouts on the specified path, target, and LUN. The default values are obtained from the Timeout & Protect mode page if supported; otherwise they're 60:90:10:10 (in seconds).
Specify the geometry explicitly; this overrides the geometry from the BIOS and the partition table. The arguments are:
  • heads and sectors — report this many heads (and optionally, sectors) to for hard disks (default is 64 heads and 32 sectors). This information is needed only to let fdisk write the correct boot cylinder for booting.
  • path_ID — the number of the controller to use, where the first controller is 0 (the default).
  • target — for IDE, this is the master (0) or slave (1); for other drivers, it's the device ID. The default is 0.
  • lun — the Logical Unit Number. The default is 0.
Set the verbosity level on the specified path, target, and LUN. If you don't specify a level, increments the current level by one.


The provides common access methods (CAMs) for hard disk devices.