1.Dd August 27, 1993 2.Dt CH 4 3.Os FreeBSD 4.Sh NAME 5.Nm ch 6.Nd scsi media-changer (juke box) driver 7.Sh SYNOPSIS 8.Nm device-driver ch 9.Op Ar count 10.Sh DESCRIPTION 11The 12.Xr ch 13driver provides support for a 14.Em scsi 15juke box. It allows many slots of media to be multiplexed between a number 16of drives. 17.Pp 18A scsi adapter must also be separatly configured into the system 19before a scsi changer can be configured. 20.Pp 21As the scsi adapter is probed during boot, the 22.Em SCSI 23bus is scanned for devices. Any devices found which answer as 'Changer' 24type devices will be 'attached' to the 25.Nm 26driver. The first found will be attached as 27.Em ch0 28and the next, 29.Em ch1 30etc. 31.Pp 32 33.Sh KERNEL CONFIGURATION 34In configuring, if an optional 35.Ar count 36is given in the specification, that number of scsi media changers 37are configured; Most storage for them is allocated only when found 38so a large number of configured devices is cheap. (once the first 39has included the driver). 40 41.Pp 42.Sh IOCTLS 43The following 44.Xr ioctl 2 45call applies to the changer. It is defined in 46in the header file 47.Em sys/chio.h. 48 49.Bl -tag -width DIOCSDINFO 50CHIOOP 51This appears to be a 'do-everything' call. 52.El 53.Sh NOTES 54The 55.Nm 56driver was added to the system by 57 Stefan Grefen (grefen@goofy.zdv.uni-mainz.de) 58who apparently had such a device 59however It appears as though no-one I have heard of has ever used this 60driver. If you use it please let me know so I can test changes. 61Stefan appears to have suffered net.death (or at least net.disconnection). 62I (julian) have never used this device. If you do please re-write this 63man page and send it to me.. 64 65.Sh FILES 66.Bl -tag -width /dev/ch[0-9] -compact 67.It Pa /dev/ch[0-9] 68device entries 69.El 70.Sh DIAGNOSTICS 71None. 72.Sh SEE ALSO 73.Xr sd 4 74.Xr st 4 75.Xr cd 4 76.Sh HISTORY 77The 78.Nm 79driver appeared in 386BSD 0.1 80 81