Installation guide

Linux device-naming convention
157
Additional Notes
Linux device-naming convention
The four high-level device drivers in Linux are:
sd - Direct access (disks)
sg - SCSI generic interface
sr - Data CD-ROMs
st - Tapes
The
sg driver is a character-based device while the other three
drivers are block-based devices. The
sg driver is used primarily for
scanners, CD writers, and printers. The
sg device files are
dynamically mapped to SCSI IDs/LUNs on the SCSI bus starting
with the first SCSI controller.
Block device file names
A native device file name for block devices takes the following form:
/dev/sd LN
where:
◆ L is a letter denoting the physical drive.and Configuring the HBA
and Driver.
◆ N is a number denoting the partition on that physical drive.
Note: Usually, the partition number is not included when referring to the
entire drive.
Following this format, the filenames are as follows:
/dev/sd[a-d][a-z][1-15]
The Linux kernel reserves 16 major numbers for SCSI devices. Each
major number can have zero to 255 minor numbers. These minor
numbers include the partitions for a SCSI device. Linux supports one
to 15 partitions per disk device. Partitions 1 through 4 are the primary
partitions, while partitions 5 and greater are the logical or extended
partitions. These limitations are specific to the Intel platform. By
default, slices are not used in Linux.
Therefore, the product of 16 major numbers and 16 minor numbers
yields 256 SCSI devices. As a result, the kernel is able to scan logical
devices ranging from 0 through 255. Red Hat Linux distributions and