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BIO(4) Device Drivers Manual BIO(4)

bioblock I/O ioctl tunnel pseudo-device

pseudo-device bio [count]

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.

If count is given in the specification, and is greater than 0, a maximum of one bio device is created.

The following device drivers register with bio for volume management:

ami(4)
American Megatrends Inc. MegaRAID PATA/SATA/SCSI RAID controller
arc(4)
Areca Technology Corporation SAS/SATA RAID controller
cac(4)
Compaq Smart ARRAY 2/3/4 SCSI RAID controller
ciss(4)
Compaq Smart ARRAY 5/6 SAS/SATA/SCSI RAID controller
ips(4)
IBM SATA/SCSI ServeRAID controller
mfi(4)
LSI Logic & Dell MegaRAID SAS RAID controller
mpi(4)
LSI Logic Fusion-MPT Message Passing Interface
mpii(4)
LSI Logic Fusion-MPT Message Passing Interface II
softraid(4)
Software RAID

The following device drivers register with bio to provide enclosure management:

safte(4)
SCSI Accessed Fault-Tolerant Enclosure
ses(4)
SCSI Enclosure Services

The following ioctl calls apply to the bio device:

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.
Retrieve number of volumes and physical disks for a specific device.
Retrieve detailed information for the specified physical disk. Information returned can include status, size, channel, target, lun, vendor name, serial number and processor device (ses or safte).
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.
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 hardware.

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 governed by ses(4) or safte(4) and the hardware supports hardware blinking.

Alter the state of specified physical disk. Supported states are: create hot-spare, online disk and offline disk.

The following ioctl calls apply to the bio device only when talking to a softraid(4) device:

Create a new volume or assemble an existing volume. The volume will be attached as a system disk, if this capability is supported by the volume discipline.
Remove system disk (if present) and disassemble the softraid(4) volume.
Dispatch a discipline specific ioctl.

/dev/bio
ioctl tunnel device

ioctl(2), softraid(4), bioctl(8)

The bio driver first appeared in OpenBSD 3.2.

The bio driver was written by Niklas Hallqvist <niklas@openbsd.org>. The API was written by Marco Peereboom <marco@openbsd.org>.

July 16, 2013 OpenBSD-5.5