BIO(4)                  NetBSD Kernel Interfaces Manual                 BIO(4)

     bio -- Block IO ioctl tunnel pseudo-device

     pseudo-device bio

     #include <dev/biovar.h>

     The bio driver provides userland applications ioctl(2) access to devices
     otherwise not found as /dev nodes.  The /dev/bio device node operates by
     delegating ioctl calls to a requested device driver.  Only drivers which
     have registered with the bio device can be accessed via this interface.

     The following device drivers register with bio for volume management:

           arcmsr(4)     Areca Technology Corporation SATA RAID controller
           ataraid(4)    Software BIOS RAID
           cac(4)        Compaq RAID array controller
           ciss(4)       Compaq Smart ARRAY 5/6 SAS/SATA/SCSI RAID controller
           mfi(4)        LSI Logic & Dell MegaRAID SAS RAID controller
           mfii(4)       LSI Logic MegaRAID SAS Fusion RAID controller
           mpii(4)       LSI Logic Fusion-MPT Message Passing Interface II
           mpt(4)        LSI Fusion-MPT RAID controller

     The following ioctl calls apply to the bio device:

     BIOCLOCATE        Locate a named device and give back a cookie to the
                       application for subsequent ioctl calls.  The cookie is
                       used to tunnel further ioctls to the right device.

     BIOCINQ           Retrieve number of volumes and physical disks for a
                       specific device.

     BIOCDISK          Retrieve detailed information for the specified physi-
                       cal disk.  Information returned can include status,
                       size, channel, target, lun, vendor name, serial number,
                       and processor device (ses).

     BIOCDISK_NOVOL    Is just the same as BIOCDISK but doesn't require the
                       disks to be in volume sets, so this applies to any
                       physical disk connected to the controller.

                       Note: this ioctl might not be supported on all hard-
                       ware.  It is a NetBSD extension of bio.  It is sup-
                       ported by arcmsr(4), ciss(4), and mpt(4).  It is also
                       supported by cac(4), but handled exactly the same as

     BIOCVOL           Retrieve detailed information for the specified volume.
                       Information returned can include status, size, RAID
                       level, number of disks, device name association (sd?)
                       and vendor name.

     BIOCALARM         Control the alarm beeper on the device.  Supported
                       states are: disable alarm, enable alarm, silence alarm,
                       status and test alarm.

                       Note: These options might not be supported on all hard-
                       ware.  It is supported by arcmsr(4), mfi(4), and

     BIOCBLINK         Blink an LED of the specified physical disk.  Supported
                       blink states are: blink LED, unblink LED and blink
                       alarm LED.

                       Note: This option is only supported if the disk is gov-
                       erned by ses(4) and the hardware supports hardware
                       blinking.  It is supported by ciss(4), mfi(4), and

     BIOCSETSTATE      Alter the state of specified physical disk.  Supported
                       states are: create/remove hot-spare, create/remove pass
                       through disk, start/stop consistency check in a volume,
                       online disk and offline disk, and a manual rebuild
                       kick-off designation.

                       Note: These options might not be supported on all hard-
                       ware.  Some of these options are supported by
                       arcmsr(4), mfi(4), and mfii(4).

                       Online, offline and hotspare designations are supported
                       by mfi(4) and mfii(4), plus a rebuild designation is
                       supported by mfii(4); all four of these state options
                       are the original states from OpenBSD, the other
                       options, including hotspare unmarking, being NetBSD
                       extensions of bio.

                       Hotspare, pass through and consistency check options
                       are supported by arcmsr(4).

     BIOCVOLOPS        For operations in volume sets.  It's able to create and
                       remove a volume set in a supported RAID controller.

                       Note: this ioctl might not be supported on all hard-
                       ware.  It is a NetBSD extension of bio, and is sup-
                       ported by arcmsr(4).

     The bioctl(8) utility can be used to perform the above controls from the
     userland.  Additionally, since BIOCVOL volume status is normally dupli-
     cated into sysmon_envsys(9) sensors of ENVSYS_DRIVE type, it is also
     available through envsys(4), and can be monitored with envstat(8) and

             ioctl tunnel device
             powerd script for drive sensors

     ioctl(2), envsys(4), bioctl(8), envstat(8), powerd(8), sysmon_envsys(9)

     The bio driver first appeared in OpenBSD 3.2 and NetBSD 4.0.

     The bio driver was written by Niklas Hallqvist <>.  The
     API was written by Marco Peereboom <> and was extended
     even more for NetBSD by Juan Romero Pardines <>.

NetBSD 9.0                        May 9, 2019                       NetBSD 9.0

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