ch - scsi media-changer (juke box) driver
ch? at scsibus? target ? lun ?
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
into the system before a SCSI changer can be configured.
As the SCSI adapter is probed during boot, the SCSI bus is
devices. Any devices found which answer as "Changer" type
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
ch unit a device should come on-line as; refer to scsi(4)
for details on
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
cheap (once the first has included the driver).
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.
/dev/ch[0-9] device entries
cd(4), intro(4), scsi(4), sd(4), st(4)
These manpages were derived from the FreeBSD documentation
of the generic
SCSI drivers. Since naming and calling conventions may have
suffered port specific changes, please review the appropriate header
files and configuration file for your port.
The ch driver appeared in 386BSD 0.1.
OpenBSD 3.6 March 28, 1997
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