IBM eX5 Implementation Guide

440 IBM eX5 Implementation Guide

8.7.8 SAN storage reference and considerations

BladeCenters are designed to provide blades with usable storage via the external storage

attachment due to the blade’s compact design. We highly recommend that you have an

understanding of the terms and methods that relate to SAN attachment. SAN is out of the

scope of this IBM Redbooks publication; however, we provide information related to the

protocols that are used to attach to SAN and boot from SAN.

SAN storage attachment terms

The primary purpose of the storage area network (SAN) is to transfer data between computer

systems and storage elements. The following list describes each of the most common SAN

protocols and their characteristics:

򐂰 Fibre Channel (FC)

The Fibre Channel Protocol (FCP) is the interface protocol of SCSI on FC. FCP is a

transport protocol that predominantly transports SCSI commands over FC networks. FC is

the prevalent technology standard in the SAN data center environment. Typical

requirements for this configuration are an FC host bus adapter (HBA) and FC SAN

infrastructure. Despite its name, FC signaling can run on both twisted-pair copper wire and

fiber optic cables.

򐂰 Fibre Channel over Ethernet (FCoE)

FCoE is the transport, or mapping, of encapsulated FC frames over the Ethernet. The

Ethernet provides the physical interface, and FC provides the transport protocol. The

system setup for FCoE requires the Converged Network Adapter (CNA) to pass both

network and storage data that is connected to a 10 Gb converged network infrastructure.

򐂰 Internet SCSI (iSCSI)

iSCSI is an Internet Protocol (IP)-based storage networking standard for linking data

storage facilities. The protocol allows clients (called

initiators) to send SCSI commands to

SCSI storage devices (targets). A hardware initiator might improve the performance of the

server. Often, iSCSI is seen as a low-cost alternative to FC.

򐂰 Serial-attached SCSI (SAS)

SAS uses point-to-point connection. The typical SAS throughput is 6 Gbps full duplex. If a

complex SAN configuration is not necessary, SAS is a good choice although performance

and distance are limited compared to the other solutions.

Booting from SAN

This section provides useful guidelines about booting from SAN:

򐂰 Check to make sure that UEFI recognizes the HBA. Select UEFI  System Settings 

Adapter and UEFI Drivers. When you press Enter, the respective HBA is visible, as

shown in Figure 8-71. If it is not visible, you might need to reflash the UEFI, IMM, and

firmware of the HBA and check again.

Red Hat RHEL https://www.redhat.com/support/ Documentation, driver, and OS

update

Novell SLES http://www.novell.com/support/ Documentation, driver, and OS

update

VMware vSphere http://downloads.vmware.com/d/ Documentation, driver, and OS

update

Vendor Product Address Available support

Chapter 8. IBM BladeCenter HX5 441

Figure 8-71 Adapters visible in UEFI

򐂰 If you do not have internal drives installed, disable the onboard SAS RAID Controller in

UEFI by navigating to System Settings  Devices and IO ports  Enable/Disable

Onboard Devices and disabling the SAS Controller or Planar SAS.

򐂰 Set the HBA as the first device in the Option ROM Execution Order by selecting System

Settings  Devices and IO Ports  Set Option ROM Execution Order.

򐂰 All operating systems, except Windows 2008 and SLES 11 SP1, now have Legacy Only

set as their first boot device.

򐂰 Remove all devices that might not host an operating system from the boot order. The

optimal minimum configuration is CD/DVD and Hard Disk 0. For existing operating

systems only, set Legacy Only as the first boot device.

򐂰 You must set the BIOS on the HBA to Enabled.

򐂰 Make sure that the logical unit number (LUN) that will host the operating system

installation is accessible through only one path on the SAN at the time of the installation.

򐂰 Verify that your HBA can see a LUN from your storage.

򐂰 After installation, do not forget to install the multipath driver

before you set more than one

path if you have more than one path to the LUN.