Installation guide

9.6.2 Examples for Creating Raw Partitions

Specific system administration is required before you can enable and use raw devices. The available tools to

configure devices depend on the distribution configuration.

You must allocate physical disk space in partitions on the disks where you want to set up raw devices. The

physical I/O subsystem can be on either SCSI or EIDE devices.

Note

You can create partitions with the Linux default fdisk(8) utility. You must have root privileges to use the

command fdisk. See the fdisk(8) man pages for a complete description of the command.

Example

This example shows how to set up partitions as raw devices, on four SCSI disks in the system—sda, sdb, sdc,

and sdd.

1. Start fdisk on /dev/sdd:

# fdisk /dev/sdd

The system returns:

The number of cylinders for this disk is set to 8683

....

Command (m for help):

2. Enter p to print the current partition layout. The output is:

Disk /dev/sdd: 64 heads, 32 sectors, 8683 cylinders

Units = cylinders of 2048 * 512 bytes

Device Boot Start End Blocks Id System

/dev/sdd1 1 7499 7678960 83 Linux

/dev/sdd2 7500 8012 525312 82 Linux swap

/dev/sdd4 8013 8683 687104 5 Extended

Example

This example shows the extended partition (sdd4) has 687,104 free blocks, starting from 8013 and ending at

8683. You can assign the remaining partitions later. This example assigns an additional partition for raw bound

disk I/O:

1. Use the n command to create a new partition, and enter l (for "logical") at this prompt:

Command (m for help): n

Command action

l logical (5 or over)

p primary partition (1-4)

2. Accept the default by pressing Enter when you see:

First cylinder (8013-8683, default 8013):

3. Accept the default by pressing Enter again, when you see:

Last cylinder or +size or +sizeM or +sizeK

(8013-8683, default 8683): 8269

Installation Guide for Linux

Postinstallation Tasks