autoloading sg driver during boot

[Aleksandar Milivojevic]

Paul Howarth wrote:
> Aren't the tape and the autochanger using different SCSI IDs or LUNs?

Yes, they are.  Autochanger is SCSI ID 0, tape is SCSI ID 1.  The tape 
gets /dev/st0* and /dev/nst0* on boot, and udev also creates couple of 
symbolic links for it.  Once I do "modprobe sg", /dev/sg1 is 
additionally created for tape (different major device number than st* 
and nst*, of course), and /dev/sg0 for autochanger.

> Try this:
> Manually load the sg module so that the sg devices get created.
> What do you then get for:
> $ udevinfo -a -p `udevinfo -q path -n /dev/sg0`
> and
> $ udevinfo -a -p `udevinfo -q path -n /dev/sg1`

It gives this for sg0:

   looking at class device '/sys/class/scsi_generic/sg0':
     SYSFS{dev}="21:0"

follow the class device's "device"
   looking at the device chain at 
'/sys/devices/pci0000:00/0000:00:06.0/host0/target0:0:0/0:0:0:0':
     BUS="scsi"
     ID="0:0:0:0"
     SYSFS{detach_state}="0"
     SYSFS{device_blocked}="0"
     SYSFS{model}="EXB-210         "
     SYSFS{queue_depth}="2"
     SYSFS{rev}="1.10"
     SYSFS{scsi_level}="3"
     SYSFS{state}="running"
     SYSFS{timeout}="0"
     SYSFS{type}="8"
     SYSFS{vendor}="EXABYTE "

   looking at the device chain at 
'/sys/devices/pci0000:00/0000:00:06.0/host0/target0:0:0':
     BUS=""
     ID="target0:0:0"
     SYSFS{detach_state}="0"

   looking at the device chain at 
'/sys/devices/pci0000:00/0000:00:06.0/host0':
     BUS=""
     ID="host0"
     SYSFS{detach_state}="0"

   looking at the device chain at '/sys/devices/pci0000:00/0000:00:06.0':
     BUS="pci"
     ID="0000:00:06.0"
     SYSFS{class}="0x010000"
     SYSFS{detach_state}="0"
     SYSFS{device}="0x001f"
     SYSFS{irq}="5"
     SYSFS{subsystem_device}="0x000f"
     SYSFS{subsystem_vendor}="0x9005"
     SYSFS{vendor}="0x9005"

   looking at the device chain at '/sys/devices/pci0000:00':
     BUS=""
     ID="pci0000:00"
     SYSFS{detach_state}="0"



and this for sg1:

   looking at class device '/sys/class/scsi_generic/sg1':
     SYSFS{dev}="21:1"

follow the class device's "device"
   looking at the device chain at 
'/sys/devices/pci0000:00/0000:00:06.0/host0/target0:0:1/0:0:1:0':
     BUS="scsi"
     ID="0:0:1:0"
     SYSFS{detach_state}="0"
     SYSFS{device_blocked}="0"
     SYSFS{model}="Mammoth2        "
     SYSFS{queue_depth}="2"
     SYSFS{rev}="v07g"
     SYSFS{scsi_level}="3"
     SYSFS{state}="running"
     SYSFS{timeout}="900"
     SYSFS{type}="1"
     SYSFS{vendor}="EXABYTE "

   looking at the device chain at 
'/sys/devices/pci0000:00/0000:00:06.0/host0/target0:0:1':
     BUS=""
     ID="target0:0:1"
     SYSFS{detach_state}="0"

   looking at the device chain at 
'/sys/devices/pci0000:00/0000:00:06.0/host0':
     BUS=""
     ID="host0"
     SYSFS{detach_state}="0"

   looking at the device chain at '/sys/devices/pci0000:00/0000:00:06.0':
     BUS="pci"
     ID="0000:00:06.0"
     SYSFS{class}="0x010000"
     SYSFS{detach_state}="0"
     SYSFS{device}="0x001f"
     SYSFS{irq}="5"
     SYSFS{subsystem_device}="0x000f"
     SYSFS{subsystem_vendor}="0x9005"
     SYSFS{vendor}="0x9005"

   looking at the device chain at '/sys/devices/pci0000:00':
     BUS=""
     ID="pci0000:00"
     SYSFS{detach_state}="0"

-- 
Aleksandar Milivojevic <amilivojevic at pbl.ca>    Pollard Banknote Limited
Systems Administrator                           1499 Buffalo Place
Tel: (204) 474-2323 ext 276                     Winnipeg, MB  R3T 1L7