i2o_bs - Block Storage OSM for I2O
disk@local target id#:a through u
disk@local target id#:a through u raw
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 ran-
dom 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 Intelli-
gent 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 there-
fore 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
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 sys-
tems or system reserved area.
Fdisk partition 0 is to access the entire disk and is gen-
erally used by the fdisk(1M) program.
cn controller n
dn instance number
sn UNIX system slice n (0-15)
pn fdisk partition (0)
for descriptions of the following attributes:
| ATTRIBUTE TYPE | ATTRIBUTE |ALUE
| Architecture | x86 |
fdisk(1M), format(1M)mount(1M),lseek(2), read(2), write(2),
readdir(3C), vfstab(4), acct(3HEAD), attributes(5), dkio(7I)
Man(1) output converted with