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dks(7M)								       dks(7M)

NAME    [Toc]    [Back]

     dks - dksc	(SCSI) disk driver

SYNOPSIS    [Toc]    [Back]


DESCRIPTION    [Toc]    [Back]

     The dksc driver supports all disk types that use a	SCSI command set.
     This includes traditional parallel	SCSI as	well as	Fibre Channel
     Arbitrated	Loop and Fibre Channel Fabric devices (devices connected
     through a Fibre Channel switch).  Currently, 8 bit	parallel SCSI (also
     called narrow SCSI) allows	up to seven SCSI drives	attached per SCSI bus,
     16	bit parallel SCSI (also	called wide SCSI) allows 15 drives.  Fibre
     Channel Arbitrated	Loop (FC-AL) allows up to 125 drives (some
     implementations limit the number to 110).	The maximum number addressable
     through Fibre Channel Fabric has no theoretical limit.  However,
     practical considerations do limit the number to 252 drives	for current
     adapters.	Each drive (a RAID controller is considered a "drive" for
     these purposes) can support a number of logical units (luns).  The
     current limit depends on the host adapter.	 It varies from	8 to 255.
     Each unit (or lun)	can have up to 16 partitions in	use, three of which
     (8, 9, and	10) are	special	(see below).

     Disk devices are named according to the following formats (jaguar drives
     are no longer supported):

     Parallel SCSI and FC-AL    [Toc]    [Back]


     Fibre Channel Fabric    [Toc]    [Back]


     Note that the Fabric device names always specify the lun#,	even if	it is
     zero.  The	rdsk devices use a raw interface to communicate	with the disk,
     while the dsk devices use a block interface.  The controller#, drive#,
     and lun# are used to indicate SCSI	controller number, target ID, and
     logical unit number, respectively.	 The nodename and port#	are used to
     indicate the Fibre	Channel	world wide name	(WWN) and the device port
     number (normal Fibre Channel disks	have two ports).  spartition#, vh, and
     vol indicate a partition of the disk.  The	vh and vol devices are only in
     the rdsk directory, since they are	normally used only for ioctl and raw

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dks(7M)								       dks(7M)

     The standard partition allocation by Silicon Graphics has root on
     partition 0, swap on partition 1, and (optionally)	/usr on	partition 6.
     Some systems, such	as the Indy, are shipped from the factory with a
     single filesystem on the system disk for ease of administration.  In this
     case, partition 6 is not used.  Partition 7 (when present), normally maps
     the entire	usable portion of the disk (excluding the volume header).
     Partition 8 (vh) maps the volume header (see prtvtoc(1M), dvhtool(1M)).
     Partition 10 (vol)	maps the entire	drive.	Partition 9 is reserved, but
     is	not used for disks with	the dksc driver.

     In	current	releases, these	devices	are part of the	hardware graph
     hwgfs(4), and are created dynamically as the disk partitions are changed.
     Therefore MAKEDEV no longer needs to be run, nor does it need to be
     modified to create	additional partition devices.  The partitions will be
     created/updated whenever a	disk is	opened,	such as	when a filesystem is
     mounted, or when programs such as fx(1M) and prtvtoc(1M) access the disk.
     For devices that are hot-plugged, the bus that they are plugged into must
     be	reprobed and reconfigured (see scsiha(1m) and ioconfig(1M)) in order
     for the partitions	to be created.

     For removable media devices, mediad(1M), if running, will cause these
     updates to	occur after media changes. In the absence of mediad, the user
     will need to run code or execute commands that will cause an open against
     the volume	header.	fx(1M) or prtvtoc(1M) are two examples of commands
     that will do this,	as well	as the DIOCGETVH ioctl (see below) issued by a

     The standard configuration	has /dev/root linked to	partition 0 of the
     system disk, with /dev/swap linked	to partition 1 of the system disk, and
     /dev/usr linked to	partition 6 of the system disk.	 Systems that do not
     use partition 6 as	shipped, instead using just the	s0 and s1 partitions,
     still have	a link made.  There is no attempt to make the link to the
     device used for the /usr filesystem in the	fstab(4) file, if present,
     even if it	uses a different device.  Option disks normally	use the	s7
     partition as a single filesystem, containing the whole usable portion of
     the disk.

IOCTL FUNCTIONS    [Toc]    [Back]

     As	well as	normal read and	write operations, the driver supports a	number
     of	special	ioctl(2) operations when opened	via the	character special file
     in	/dev/rdsk.  Command values for these are defined in the	system include
     file <sys/dkio.h>,	with data structures in	<sys/dksc.h>.
     These ioctl operations are	intended for the use of	special-purpose	disk
     utilities.	 Many of them can have drastic or even fatal effects on	disk
     operation if misused; they	should be invoked only by the knowledgeable
     and with extreme caution!

     A list of the ioctl commands supported by the dks driver is given below.

	  Adds a block to the badblock list.  The argument is the logical
	  block	number (not a pointer) on the drive.  For some makes of

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dks(7M)								       dks(7M)

	  drives, the spared block must	be written before the sparing takes
	  effect.  Only	programs running with superuser	permissions can	use
	  this ioctl.

	  The first SCSI_DEVICE_NAME_SIZE bytes	(currently 28) of the SCSI
	  inquiry data for the drive is	returned to the	caller.	 The argument
	  is a pointer to a char array of at least this	size.  This contains
	  vendor and drive specific information	such as	the drive name and
	  model	number.	 See a SCSI command specification for details on the
	  structure of this buffer.

	  Formats the entire drive.  Any information on	the drive is lost.
	  The grown defect list	(blocks	spared with DIOCADDBB) is empty	after
	  formatting is	complete, blocks previously in the grown defect	list
	  are no longer	spared.

	  Reads	the disk volume	header from the	driver into a buffer in	the
	  calling program.  The	argument in the	ioctl call must	point to a
	  buffer of size at least 512 bytes.  The structure of the volume
	  header is defined in the include file	<sys/dvh.h>.  The
	  corresponding	call DIOCSETVH sets the	drivers	idea of	the volume
	  header; in particular, the drivers idea of the partition sizes and
	  offsets is changed.

	  Issues a PREVENT ALLOW MEDIA REMOVAL command to the opened device.
	  The first bit	of the arg is or'd into	byte 4 of the SCSI command.
	  See a	SCSI command specification for details on this command.

	  The argument is a pointer to a struct	dk_ioctl_data.	The i_addr
	  field	points to a structure like:

	       structure defect_list {
		    struct defect_header defhdr;
		    struct defect_entry	defentry[NENTS];

	  The i_len field is set to the	total length of	the structure, which
	  must be less than NBPP from <sys/param.h>; at	most NENTS defects are
	  returned.  The actual	number of defects can be determined by
	  examining the	defhdr.defect_listlen value, which is the number of
	  bytes	returned.  This	must be	divided	by the size of the applicable
	  data structure for the type requested.  The i_page field should be
	  set to the bits identifying the badblock reporting type.  These bits
	  request the combination of manufacturer's and	grown defects; and one
	  of bytes from	index, physical	cyl/head/sec, vendor unique.  The only
	  combination that works with all currently supported SCSI disks is

									Page 3

dks(7M)								       dks(7M)

	  type cyl/head/sec; and either	combined manufacturer's	and grown
	  defects, or just manufacturer's defects.

	  The arg is a pointer to an unsigned integer.	The value returned is
	  the number of	usable sectors on the drive (as	read from the drive).

	  The arg is a pointer to a char array at least	SCSI_INQUIRY_LEN bytes
	  long.	 The SCSI inquiry data from the	device is copied to this
	  buffer.  See a SCSI command specification for	details	on the
	  structure of this buffer.

	  The argument is a pointer to a struct	dk_ioctl_data.	This allows
	  sending SELECT and SENSE commands to the drive.  See the ANSI	SCSI
	  specification	and individual manufacturer's manuals for allowed page
	  numbers and valid values.  Only programs running with	superuser
	  permissions can use the DIOCSELECT ioctl.

	  This command issues a	SCSI STARTSTOP command to the opened device.
	  The first two	bits of	the arg	are or'd into byte 4 of	the SCSI
	  command.  See	a SCSI command specification for details on this

	  issues the SCSI "Send	Diagnostic" command to the drive.  The exact
	  tests	done are manufacturer specific.	 The ioctl call	returns	0 upon
	  success, or sets errno to EIO	and returns -1 upon failure.

NOTES    [Toc]    [Back]

     Fibre Channel fabric device names are meant to separate three concepts;
     device specification, portion of device, and path to device.  Thus	the
     nodename specifies	a unique device, such as a disk	drive or a RAID
     controller.  The lun# and partition# specify which	portion	of the disk or
     RAID is accesses, and the controller# and port# specify the path the data
     and commands travel to and	from the device.  The port number will usually
     be	something that represents the difference between the 64	bit world wide
     node name and the 64 bit world wide port name.  For non-SGI devices, and
     some SGI devices that were	released after a given release of IRIX,	the
     driver may	not be able to determine a short port number.  In such cases,
     the port number will be the 64 bit	world wide port	name.

FILES    [Toc]    [Back]


									Page 4

dks(7M)								       dks(7M)

SEE ALSO    [Toc]    [Back]

     dvhtool(1M), fx(1M), prtvtoc(1M), scsiha(1M), ioconfig(1M).

									PPPPaaaaggggeeee 5555
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