Appendix a, Appendix a: device enumeration, Appendix b: local install on an ide device – Dell Intel PRO Family of Adapters User Manual

Page 19: Suse* linux enterprise server 10, Red hat enterprise linux

Advertising
background image

SUSE* Linux Enterprise Server 11

Red Hat* Enterprise Linux

SUSE* Linux Enterprise Server 10

NOTE: Currently, only SLES11 SP3 is supported. SLES provides native support for iSCSI remote booting and installing.

This means that there are no additional steps outside of the installer that are necessary to install to an iSCSI target

using an Intel Gigabit PCI Express Server Adapter. Please refer to the SLES10 documentation for instructions on how to

install to an iSCSI LU.

Red Hat Enterprise Linux

NOTE:Currently, only Red Hat Enterprise Linux 6.5 is supported. RHEL provides native support for Intel® iSCSI Boot

and installing. This means that there are no additional steps outside of the installer that are necessary to install to an

iSCSI target using an Intel Gigabit PCI Express Server Adapter. Please refer to the RHEL6.5 documentation for

instructions on how to install to an iSCSI LU.

Appendix A: Device Enumeration

The iSCSI LUs are discovered as SCSI device nodes. The enumeration of SCSI devices is dynamic. The SCSI subsystem creates

device nodes in the order that they are discovered, starting with /dev/sda and incrementing alphabetically. In the case of

iSCSI LU enumeration, local SCSI devices such as disks or USB devices affect this process. If a device node is created for a

USB device before iSCSI discovery occurs the USB device will be represented by /dev/sda and the iSCSI LUs will begin with

/dev/sdb. However, if you were to reboot this system without the USB device the iSCSI LUs will begin with /dev/sda. It is

important to configure grub correctly to point to the correct device node in order to boot from an iSCSI hard drive.

It is often the case when installing to an iSCSI LU that a device driven by the SCSI subsystem is used for the install media. For

example, using a USB flash drive for the Driver Update Media (DUM). As stated above this will affect how grub should be

configured when installing.

Here is an example of how iSCSI device node mappings might differ between installation and booting. In this example the user

is using a USB flash drive as a DUM. Because this device is being used to copy files onto the system, it is present before iSCSI

discovery occurs. However, when booting from the iSCSI Boot Disk, no USB flash drive is necessary and therefore it is not

attached.

Remote Installation:

USB flash drive or USB floppy

/dev/sda

LUN 0

/dev/sdb

LUN 1

/dev/sdc

Booting:

LUN 0

/dev/sda

LUN 1

/dev/sdb

If the USB device is attached after booting, it will be enumerated as such: USB flash drive or USB floppy /dev/sdc.

It is also possible that there are other USB devices on the system; it is the user's responsibility determine whether these will

interfere with the device node mapping during boot.

Appendix B: Local Install on an IDE Device

After performing a Local Install on an IDE device the user will need to modify grub so that when booting the root partition is

identified as a SCSI device. When installing to a local IDE disk drive the device node used will be of the form /dev/hdX, but

when this volume is exposed by the iSCSI target the initiator will see the hard drive as a SCSI device and it will be

represented as /dev/sdX. This change must be made in the grub configuration file. This type of problem exposes the necessity

Advertising