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NAME    [Toc]    [Back]

       ri - I2O RAID disk interface

SYNOPSIS    [Toc]    [Back]

       bus             i2o0       at pci2001   slot  4

       controller      i2o_bs0    at i2o0      slot  18

DESCRIPTION    [Toc]    [Back]

       The  ri  driver  supports  32-bit and 64-bit PCI backplane
       RAID controllers with Intelligent I/O (I2O) host interface
       supporting  backend  SCSI channels.  I2O is an open architecture
 for developing device drivers that is  independent
       of  the  operating  system, processor platform, and system
       I/O bus.  The communication model is based on  a  messagepassing
  protocol reducing the number of driver interfaces
       needed.  A single driver called an Operating  System  Module(OSM)
  is  provided  to support all Block Storage class
       devices.  Any RAID system that supports the I2O  interface
       functions  with this driver.  These devices are designated
       as ri to distinguish them  from  ra,  re,  and  rz  (SCSI)

       The  StorageWorks  Command  Console Utility (SWCC) is supported
 for online configuration and monitoring of I2O raid

       The  following  rules  are used to determine the major and
       minor numbers that are associated with an ri type disk.  A
       dynamic  major  number  is  used  to  represent  ri  block
       devices, and is assigned during initial configuration. The
       current major number can be determined using the following

       # /sbin/devswmgr -getnum i2o_bs

       The preceding command displays the driver switch  reservation
  list,  showing  the device instance and major number
       for the i2o_bs driver.  An alternative method is:

       # /sbin/sysconfig -q i2o_bs

       The highest 14 bits of the 20-bit minor number  represents
       a  particular  Block Storage device, while lowest six bits
       of the minor number specify disk partitions (identified by
       the letters, a through h) on that device.

       The device special file names associated with ri disks are
       based on conventions that are closely associated with  the
       minor  number  assigned  to the disk.  The standard device
       names begin with ri for block special files  and  rri  for
       character  (raw)  special  files.  Following the ri is the
       unit number and then a letter, a through  h,  that  represents
  the partition.  Throughout this reference page, the
       question mark (?) character represents the unit number  in
       the  name  of  the device special file.  For example, ri?b
       could represent ri0b, ri1b, and so on.

       A disk can be accessed through either  the  block  special
       file  or  the  character  special file.  The block special
       file accesses the disk  using  the  file  system's  normal
       buffering  mechanism.   Reads and writes to the block special
 file can specify any size.   This  capability  avoids
       the  need  to limit data transfers to the size of physical
       disk records and to calculate offsets within disk records.
       The file system can break up large read and write requests
       into smaller fixed size transfers to the disk.

       The character special file provides a raw  interface  that
       allows  for  direct  transmission between the disk and the
       user's read or write buffer.  A single  read/write  operation
 to the raw interface results in exactly one I/O operation.
  Consequently, raw I/O  may  be  considerably  more
       efficient for large transfers.

       For  systems  with ri disks, the first software boot after
       the system is powered on may take  longer  than  expected.
       This  delay  is normal and is caused by the software spinning
 up the ri disks.

   Disk Support    [Toc]    [Back]
       The ri driver handles all disk drives  that  can  be  connected
  to  the  I2O  RAID controller.  To determine which
       drives are supported for specific CPU types  and  hardware
       configurations, see the hardware installation and configuration
 information for your I2O system.

       I2O RAID Controllers are viewed in all cases  as  RI  type
       disks.  There  are some notable differences that should be
       taken into consideration when configuring a  RAID  device:
       Currently  only  sector  sizes of 512 bytes are supported.
       Logical Volume sizes are not fixed sizes  as  compared  to
       other  disk  devices.   The  size of the Logical Volume is
       configurable based on needs.  The dynamic nature of  Logical
 Volume sizes is dealt with by defining RAID devices as
       DYNAMIC.  Only partitions a, b, c, and g are defined.   If
       necessary,  the  disklabel(8) command can be run to change
       and define partitions for RAID devices

       Usually, the ri?a partition is used for the root file system
  and  the  ri?b  partition as a paging area.  The ri?c
       partition can be used for disk-to-disk copying because  it
       maps the entire disk.

       The  starting location and length (in 512 byte sectors) of
       the disk partitions of each drive are shown in the following
  table.  Partition  sizes  can be changed by using the
       disklabel(8) command.

       I2O RAID partitions for systems based  on  the  Alpha  AXP

            disk start     length                ri?a 0    131072
            ri?b 131072    262144       ri?c 0    end  of   media
            ri?d 0    0          ri?e 0    0          ri?f 0    0
            ri?g 393216  end of media      ri?h 0    0

FILES    [Toc]    [Back]



SEE ALSO    [Toc]    [Back]

       RAID(7), SCSI(7), tz(7), rz(7), disklabel(8),  MAKEDEV(8),

[ Back ]
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