IBM DS8000 Missing device files, Example A-10 Create new special device files for Scsi disks

Each SCSI device can have up to 15 partitions, which are represented by the special device files /dev/sda1, /dev/sda2, and so on. The mapping of partitions to special device files and major and minor numbers is shown in Table A-2.

Table A-2 Minor numbers, partitions and special device files

Major number	Minor number	Special device file	Partition
8	0	/dev/sda	all of 1st disk
8	1	/dev/sda1	1st partition of 1st disk
	...
8	15	/dev/sda15	15th partition of 1st
			disk
8	16	/dev/sdb	all of 2nd disk
8	17	/dev/sdb1	1st partition of 2nd disk
	...
8	31	/dev/sdb15	15th partition of 2nd
			disk
8	32	/dev/sdc	all of 3rd disk
	...
8	255	/dev/sdp15	15th partition of 16th
			disk
65	0	/dev/sdq	all of 16th disk
65	1	/dev/sdq1	1st partition on 16th
			disk
...	...

Missing device files

The Linux distributors do not always create all the possible special device files for SCSI disks. If you attach more disks than there are special device files available, Linux will not be able to address them. You can create missing device files with the mknod command. The mknod command requires four parameters in a fixed order:

￿The name of the special device file to create

￿The type of the device, b stands for a block device, c for a character device

￿The major number of the device

￿The minor number of the device

Refer to the manpage of the mknod command for more details. Example A-10shows the creation of special device files for the 17th SCSI disks and its first three partitions.

Example: A-10 Create new special device files for SCSI disks

mknod /dev/sdq b 65 0 mknod /dev/sdq1 b 65 1 mknod /dev/sdq2 b 65 2 mknod /dev/sdq3 b 65 3

Appendix A. Open systems operating systems specifics 359