Re: Solaris device tree question

[mengel@fnal.gov]

On 19 Jan, Bob Van Cleef wrote:
>  On Tue, 19 Jan 1999, chuck wrote:
>  
> > The device remapping issue can be a nightmare in Solaris and
> > there's not a lot you can do short of booting Linux.  There's
> > nothing like throwing a new SCSI card into a machine and spending
> > the next 4 hours trying to recover from that.
>  
>  Unfortunately, Linux has the same kind of problem with the remapping of
>  SCSI devices...  Remove a SCSI tape drive from your backup system for
>  service, reboot the system, and reconfigure your backup software... 

We've come up with the following script, which reads /proc/scsi/scsi
on Linux and builds controller/bus based device names for scsi tape and
scsi passthrough devices:

- - - - - - - - - - - - - cut here - - - - - - - - - - - - - - - - - 
#!/bin/sh
# This script reads /proc/scsi/scsi and for each device it creates a
# special file /dev/scsi/sg<BUS>d<SCSI ID> with the
# minor number = the index of the device in /proc/scsi
#
# It also creates the files /dev/tape/tp<BUS>d<SCSI ID> and
#                           /dev/tape/tp<BUS>d<SCSI ID>n
# again with the minor number  = the index of the device in /proc/scsi for
# the rewind and norewind tape devices.
#
# This script is neccessary because the linux /dev/st and /dev/sg devices
# change as devices are added to a bus
#
# The script should normally be run at boot time or if the scsi
# configuration changes

TAPEDIR=/dev/rmt
SCSIDIR=/dev/sc
if [ ! -d $TAPEDIR ]            # create the dirs if they
then                            #    don't exist
  mkdir $TAPEDIR
fi
if [ ! -d $SCSIDIR ]
then
  mkdir $SCSIDIR
fi

# remove old files

rm    $TAPEDIR/tps*    $SCSIDIR/sc* 2> /dev/null

n=-1      # index of device in proc/scsi, minor # of sg device
t=-1      # index of tape devices in proc/scsi, # used in sg#

# read each record in proc scsi

cat /proc/scsi/scsi | while read a b c d e f g
do
   if [ ! $a = "Attached" ]
   then
      if [ \"$a\" = \"Host:\" ]
      then
         let n=n+1                      # increment index on first line
         bus=`echo $b|tr -d \"[a-z]\"`  #  in /proc/scsi/scsi
         let id=$f                      # get the bus and id (w/o leading 0)
         DRV=$TAPEDIR/"tps"$bus"d"$id
         SCDRV=$SCSIDIR/"sc"$bus"d"$id
      fi
      if [ \"$c\" = \"Model:\" ]        # just interesting info
      then
         vend=$b
         mod=$d
      fi
      if [ $a = "Type:" ]
      then
         if [ \"$b\" = \"Sequential-Access\" ]    # identify tape device
         then
            let t=t+1
            mknod $DRV c 9 $t           #   make the device
            mknod $SCDRV  c 21 $n       #        the scsi passthru device
         else                           # for non tape
            mknod $SCDRV  c 21 $n       #   just make scsi device
         fi
      fi
    fi
done