CH(4) BSD Programmer's Manual CH(4)NAMEch - scsi media-changer (juke box) driver
SYNOPSIS
ch? at scsibus? target ? lun ?
DESCRIPTION
The ch driver provides support for SCSI juke boxes. It allows many slots
of media to be multiplexed between a number of drives.
A SCSI adapter and a logical scsibus must also be separately configured
into the system before a SCSI changer can be configured.
As the SCSI adapter is probed during boot, the SCSI bus is scanned for
devices. Any devices found which answer as "Changer" type devices will be
"attached" to the ch driver. The first device found will be attached as
ch0 and the next ch1, etc. It is also possible to specify what ch unit a
device should come on-line as; refer to scsi(4) for details on kernel
configuration.
KERNEL CONFIGURATION
In configuring, if an optional count is given in the specification, that
number of SCSI media changers are configured. Most storage for them is
allocated only when found so a large number of configured devices is
cheap (once the first has included the driver).
IOCTLS
The following ioctl(2) call applies to the changer. It is defined in the
header file <sys/chio.h>.
CHIOOP This appears to be a "do-everything" call.
FILES
/dev/ch[0-9] device entries
SEE ALSOcd(4), intro(4), scsi(4), sd(4), st(4)DISCLAIMER
These manpages were derived from the FreeBSD documentation of the generic
SCSI drivers. Since naming and calling conventions may have diverged or
suffered port specific changes, please review the appropriate header
files and configuration file for your port.
HISTORY
The ch driver appeared in 386BSD 0.1.
MirOS BSD #10-current March 28, 1997 1
