i2o_bs(7D)							      Devices								i2o_bs(7D)

NAME

       i2o_bs - Block Storage OSM for I2O

SYNOPSIS

       disk@local target id#:a through u
       disk@local target id#:a through u raw

DESCRIPTION

       The I2O Block Storage OSM abstraction (BSA, which also is  referred to as block storage class) layer is the primary  interface that Solaris
       operating environments use to access block storage devices. A block storage device provides random access to a  permanent  storage  medium.
       The  i2o_bs  device driver uses I2O Block Storage class messages to control  the block device; and provides the same functionality (ioctls,
       for example) that is present in the Solaris device driver  like 'cmdk, dadk' on x86 for disk.  The maximum size disk supported by i2o_bs is
       the same as what is available on x86.

       The i2o_bs is currently implemented version 1.5 of Intelligent IO specification.

       The  block  files  access  the  disk using the system's normal buffering mechanism and are read and written without regard to physical disk
       records.  There is also a "raw" interface that provides for direct transmission between the disk and  the user's read or write  buffer.	 A
       single  read   or  write  call  usually results in one I/O operation; raw I/O is therefore considerably more efficient  when many bytes are
       transmitted. The names of the block files are found in /dev/dsk; the names of the raw files are found in /dev/rdsk.

       I2O associates each block storage device with a unique ID called a local target id that is assigned by I2O hardware.  This information  can
       be  acquired  by  the  block  storage  OSM  through  I2O  Block	Storage  class	messages.  For	Block  Storage	OSM,  nodes are created in
       /devices/pci#/pci# which include the local target ID as one component of device name that the node refers to.  However the /dev	names  and
       the names in /dev/dsk and /dev/rdsk do not encode the local target id in any part of the name.

	For example, you might have the following:

       /devices/				       /dev/dsk name
       ---------------------------------------------------------------
       /devices/pci@0,0/pci101e,0@10,1/disk@10:a       /dev/dsk/c1d0s0

	I/O requests to the disk must have an offset and transfer length that is a multiple of 512 bytes or the driver returns an EINVAL error.

	Slice 0 is normally used for the root file system on a disk, slice 1 is used as a paging area (for example, swap), and slice 2 for backing
       up  the entire  fdisk partition for Solaris software. Other slices may be used for usr file systems or system reserved area.

	Fdisk partition 0 is to access the entire disk and is generally used by the fdisk(1M)  program.

FILES

       /dev/dsk/cndn[s|p]n		block device

       /dev/rdsk/cndn[s|p]n	       raw device

				       where:

				       cn	controller n

				       dn	instance number

				       sn	UNIX system slice n (0-15)

				       pn	fdisk partition(0)

       /kernel/drv/i2o_bs		i2o_bs driver

       /kernel/drv/i2o_bs.conf	       Configuration file

ATTRIBUTES

       See attributes(5)
	for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |ATTRIBUTE  TYPE 	     |ATTRIBUTE 		  VALUE
       +-----------------------------+-----------------------------+
       |Architecture		     |x86			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       fdisk(1M), format(1M)mount(1M),lseek(2), read(2), write(2), readdir(3C), vfstab(4), acct.h(3HEAD), attributes(5), dkio(7I)

SunOS 5.10							    21 Jul 1998 							i2o_bs(7D)