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 man page of the mknod command for more details. Example A-10shows the creation of special device files for the 17th SCSI disk 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

After creating the device files you may have to change their owner, group, and file permission settings to be able to use them. Often, the easiest way to do this is by duplicating the settings of existing device files, as shown in Example A-11.Be aware that after this sequence of

Appendix A. Operating systems specifics

315

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Image 339
IBM DS6000 Series manual Missing device files, 315, Example A-10 Create new special device files for Scsi disks