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 BIOCDISK. 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 mfii(4). 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 mfii(4). 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 powerd(8).
/dev/bio ioctl tunnel device /etc/powerd/scripts/sensor_drive 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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