MirOS Manual: ch(4)

CH(4)                      BSD Programmer's Manual                       CH(4)

NAME

     ch - 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 ALSO

     cd(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

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