IBM TS2340 User Guide - Page 164

Solaris Device Driver (IBMtape) 10000/IBMtape@2,0:stcn lrwxrwxrwx root other 79 Aug 26 18:54 0stn -> /devices/iommu@f,e0000000/sbus@f,e0001000/QLGC,isp@3, 10000/IBMtape@2,0:stn These entries show the device hierarchy established to support I/O for an IBM SCSI tape system. The attachment path of the device special files spans from the system board, through the S-bus, to the Sun F/W SCSI adapter (supported by the QLGC, isp SCSI adapter device driver), to the IBM device at SCSI target 2 and LUN 0 (supported by the IBMtape device driver). All nine of these special files are associated with the same IBM device (device number 0). Device Behaviors Certain device behaviors are determined by which special file in the set is opened for device access. The smc special file controls only the medium changer portion of the device and accepts only medium changer operations by way of the ioctl entry point. The smc special file does not support the read and write entry points. Only one st type special file for a particular device may be opened at any one time. The smc special file may be opened concurrently with any one of the st special files. The IBMtape device driver decides which types of special files to create during installation, based on the IBM device type being configured. For the IBM 3490E Magnetic Tape Subsystem, only the eight st type special files are created. For other IBM tape drives, all nine special files shown previously are created. For IBM tape libraries and autoloaders, only a single smc special file is created. With the information from the previous command, issuing the ls -la /devices/iommu@f,e0000000/sbus@f,e0001000/QLGC,isp@3,10000 command presents further information about the same special files, as shown in the following example. Again, the actual path information specified in the command varies from system to system. crw-rw-rw- 1 bin bin 109,1696 Aug 26 18:54 IBMtape@2,0:smc crw-rw-rw- 1 bin bin 109,1664 Aug 26 18:56 IBMtape@2,0:st crw-rw-rw- 1 bin bin 109,1728 Aug 26 18:54 IBMtape@2,0:stb crw-rw-rw- 1 bin bin 109,1732 Aug 26 18:54 IBMtape@2,0:stbn crw-rw-rw- 1 bin bin 109,1688 Aug 26 18:54 IBMtape@2,0:stc crw-rw-rw- 1 bin bin 109,1752 Aug 26 18:54 IBMtape@2,0:stcb crw-rw-rw- 1 bin bin 109,1756 Aug 26 18:54 IBMtape@2,0:stcbn crw-rw-rw- 1 bin bin 109,1692 Aug 26 18:54 IBMtape@2,0:stcn crw-rw-rw- 1 bin bin 109,1668 Aug 26 18:54 IBMtape@2,0:stn These entries show the major and minor numbers associated with each special file. Here, the major number is 109 and identifies to the system that the IBMtape device driver is in support of these special files. Major numbers are assigned by the system at the time the driver is installed and vary from system to system. The nine different minor numbers are specific to the special file names and are used by the device driver to determine which special file was used to access the device and control the device behavior accordingly. For example, the minor number 1696 indicates to the driver that the device was opened by way of the smc special file. For more information on device special files and major and minor numbers, consult the Solaris mtio man pages. 146 IBM Tape Device Drivers Installation and User's Guide