scsi_device.sh

This script reads /proc/scsi/scsi and for each device it creates a special file /dev/sg/scd with the minor number equals the index of the device in /proc/scsi.

This script is neccessary because the linux /dev/st and /dev/sg devices can change dramatically as devices are added to or subtracted from a bus.

It also creates the files:
/dev/st/scd
and
/dev/st/scdn
again with the minor number equaling the index of the device in /proc/scsi for the rewind and norewind tape devices.

This script should normally be run at boot time or if the scsi configuration changes.

Here is an example of the devices created for a robotic tape library that has four SCSI tape drives, with target ID's two through five, and a library controller at target ID six.

root [805] > ls -l st sg
sg:
total 0
crw-r--r--   1 root     root      21,   0 Feb 15 10:57 sc0d2
crw-r--r--   1 root     root      21,   1 Feb 15 10:57 sc0d3
crw-r--r--   1 root     root      21,   2 Feb 15 10:57 sc0d4
crw-r--r--   1 root     root      21,   3 Feb 15 10:57 sc0d5
crw-r--r--   1 root     root      21,   4 Feb 15 10:57 sc0d6

st:
total 0
crw-r--r--   1 root     root       9,   0 Feb 15 10:57 sc0d2
crw-r--r--   1 root     root       9, 128 Feb 15 10:57 sc0d2n
crw-r--r--   1 root     root       9,   1 Feb 15 10:57 sc0d3
crw-r--r--   1 root     root       9, 129 Feb 15 10:57 sc0d3n
crw-r--r--   1 root     root       9,   2 Feb 15 10:57 sc0d4
crw-r--r--   1 root     root       9, 130 Feb 15 10:57 sc0d4n
crw-r--r--   1 root     root       9,   3 Feb 15 10:57 sc0d5
crw-r--r--   1 root     root       9, 131 Feb 15 10:57 sc0d5n

I know this is based on something I saw on the web, somewhere, but I don't have any notes telling me where. However, I pretty much rewrote the whole thing to meet my desires. So, feel free to use it anyway you want.

varyon.sh

varyoff.sh

The two other scripts do just what their names imply. The assumption is that the tape device has a SCSI target ID of 4. Again, they came from the net somewhere, so I can't take credit for them, but the author left no bread crumbs in the file. But, then again, I didn't leave any in there either.