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NetBSD 6.1.5 - man page for sd (netbsd section 4)

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SD(4)				   BSD Kernel Interfaces Manual 			    SD(4)

NAME
     sd -- SCSI and ATAPI disk driver

SYNOPSIS
     sd* at scsibus? target ? lun ?
     sd3 at scsibus0 target 3 lun 0
     sd* at atapibus? drive ? flags 0x0000

DESCRIPTION
     The sd driver provides support for SCSI bus and Advanced Technology Attachment Packet Inter-
     face (ATAPI) disks.  It allows the disk to be divided up into a set of pseudo devices called
     partitions.  In general the interfaces are similar to those described by wd(4).

     Where the wd(4) device has a fairly low level interface to the system, SCSI devices have a
     much higher level interface and talk to the system via a SCSI host adapter (e.g., ahc(4)).
     A SCSI adapter must also be separately configured into the system before a SCSI disk can be
     configured.

     When the SCSI adapter is probed during boot, the SCSI bus is scanned for devices.	Any
     devices found which answer as 'Direct' type devices will be attached to the sd driver.

     For the use of flags with ATAPI devices, see wd(4).

PARTITIONING
     On many systems disklabel(8) is used to partition the drive into filesystems.  On some sys-
     tems the NetBSD portion of the disk resides within a native partition, and another program
     is used to create the NetBSD portion.

     For example, the i386 port uses fdisk(8) to partition the disk into a BIOS level partition.
     This allows sharing the disk with other operating systems.

CONFIGURATION OPTIONS
     The following config(1) options may be applied to SCSI disks as well as to other disks.

     SDRETRIES	    Set the number of retries that will be performed for operations it makes
		    sense to retry (e.g., normal reads and writes). The default is four (4).

     SD_IO_TIMEOUT  Set amount of time, in milliseconds, a normal read or write is expected to
		    take. The defaults is sixty seconds (60000 milliseconds). This is used to set
		    watchdog timers in the SCSI HBA driver to catch commands that might have died
		    on the device.

IOCTLS
     The following ioctl(2) calls apply to SCSI disks as well as to other disks.  They are
     defined in the header file <disklabel.h>.

     DIOCGDINFO  Read, from the kernel, the in-core copy of the disklabel for the drive.  This
		 may be a fictitious disklabel if the drive has never been initialized, in which
		 case it will contain information read from the SCSI inquiry commands.

     DIOCSDINFO  Give the driver a new disklabel to use.  The driver will not write the new
		 disklabel to the disk.

     DIOCKLABEL  Keep or drop the in-core disklabel on the last close.

     DIOCWLABEL  Enable or disable the driver's software write protect of the disklabel on the
		 disk.

     DIOCWDINFO  Give the driver a new disklabel to use.  The driver will write the new disklabel
		 to the disk.

     DIOCLOCK	 Lock the media cartridge into the device, or unlock a cartridge previously
		 locked.  Used to prevent user and software eject while the media is in use.

     DIOCEJECT	 Eject the media cartridge from a removable device.

     In addition, the scsi(4) general ioctl() commands may be used with the sd driver, but only
     against the 'c' (whole disk) partition.

NOTES
     If a removable device is attached to the sd driver, then the act of changing the media will
     invalidate the disklabel and information held within the kernel.  To avoid corruption, all
     accesses to the device will be discarded until there are no more open file descriptors ref-
     erencing the device.  During this period, all new open attempts will be rejected.	When no
     more open file descriptors reference the device, the first next open will load a new set of
     parameters (including disklabel) for the drive.

FILES
     /dev/sdup	    block mode SCSI disk unit u, partition p
     /dev/rsdup     raw mode SCSI disk unit u, partition p

DIAGNOSTICS
     None.

SEE ALSO
     ioctl(2), intro(4), scsi(4), wd(4), disklabel(5), disklabel(8), fdisk(8), scsictl(8)

HISTORY
     The sd driver was originally written for Mach 2.5, and was ported to FreeBSD by Julian Elis-
     cher.  It was later ported to NetBSD.

BSD					 January 18, 1996				      BSD
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