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This section describes how to boot a cluster from the network using the Intel Preboot Execution Environment (PXE) specification. This booting process (commonly referred to as network booting) is supported by most NICs. PXE is one way to boot the storage cluster nodes.

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1. Configure the DHCP server with next-server and filename parameters.

2. Configure PortFast on the switch ports leading to the storage cluster nodes.

3. Configure the TFTP server with PXE bootstrap, configuration, and Swarm files.

4. Set up the nodes' BIOS configurations for network booting.

Setting Up the DHCP Server for PXE Booting

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The Swarm nodes are explicitly defined by MAC address to prevent Swarm from initiating an unattended boot by other servers or workstations in this example.

Configuring PortFast on Switch Ports

PortFast is a switch port configuration parameter that enables a port to bypass the listening and learning Spanning Tree states so the port immediately forwards traffic.

Verify PortFast is configured on the switch ports leading to each node if a storage cluster node is connected to a network switch. The extended time delay can prevent netboot from delivering the Swarm image to a PXE-enabled node in a timely manner if this condition is not met.

Configuring the TFTP Server

The TFTP server transfers configuration or boot files between systems in a local environment. Configure the TFTP server to load the Swarm software onto the cluster nodes after configuring the DHCP server.

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See DHCP and Boot Server Redundancy, below.

Installing and Configuring TFTP

TFTP server software is available in both free and commercial packages. UNIX distributions commonly include TFTP server software with the standard setup. The tftp-hpa package for UNIX can integrate with Swarm. Source code can be obtained from the Linux Kernel Archives website located at kernel.org/pub/software/network/tftp.

TFTP server software is also available as a binary package in many Linux distributions.

Creating the tftpboot Directory Hierarchy

Configure the server to access the network boot file directory after installing the TFTP server. This directory is typically labeled /tftpboot because TFTP is almost exclusively used for booting network devices.

A sample template is included in the samples/NetworkBoot directory of the Swarm software distribution.

Copying Kernel and fsimage

The Swarm software distribution media includes the kernel and fsimage files, which contain the Swarm embedded operating system. Copy these files to the tftpboot/profiles/castor directory on the TFTP server so they load onto each Swarm node during bootup.

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See the documentation and ZIP file in the samples/Network-Boot directory on the Swarm distribution media for help with using the PXELINUX boot loader.

DHCP and Boot Server Redundancy

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DHCP DHCP

Configure both a primary and secondary DHCP server when setting up the DHCP server. This configuration eliminates a single point of failure if one of the servers goes offline for any reason.

• See "Failover with ISC DHCP" at madboa.com/geek/dhcp-failover to set up the ISC DHCP daemon for redundancy.

• Use the primary and secondary DHCP servers as TFTP servers to provide redundancy at the network booting layer.
  Set the next-server parameter in each server to specify a separate IP address when setting up the DHCP servers. the primary or secondary DHCP server handles the PXE boot when it answers a DHCP query.

• Verify the TFTP boot servers are located in the same broadcast domain (or VLAN) as the Swarm nodes or enable a DHCP relay server on the VLAN to prevent any network interruptions.

Setting Up a Configuration File Server

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Set the value of the castor_cfg kernel configuration parameter to a URL that targets the configuration list file to implement a configuration file server as described below.

PXE Boot Example

This is an example PXELINUX configuration file located in the tftpboot/pxelinux.cfg directory on the TFTP boot server.

default profiles/castor/kernel
append initrd=profiles/castor/fsimage ramdisk_size=160000 root=/dev/ram0 
	castor_cfg=http://172.16.1.200/castor/cfg-list.txt

USB Boot Loader Example

This is an example section of the syslinux.cfg located in the root directory on the USB flash drive:

label normal
	kernel kernel
	append initrd=fsimage ramdisk_size=160000 root=/dev/ram0 
		castor_cfg=http://172.16.1.200/castor/cfg-list.txt

Configuration List file example

The castor_cfg kernel configuration parameter specifies a file containing a list of URLs for all configuration files to be loaded by a Swarm node. Swarm configuration files are evaluated in the order in which they are listed in the configuration list file.

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See Managing Configuration Settings

Disabling Monitor Power-Saving Activation

Add the following kernel option to the APPEND line in either the syslinux.cfg file on the Swarm USB key or in the PXE boot configuration file to disable the monitor power-saving feature from activating while connected to a Swarm storage node.

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This feature defaults to 10 minutes. A value of 0 disables the blank timer. Listed below are examples:

PXE Boot Example

This is a PXELINUX configuration file from the tftpboot/pxelinux.cfg directory on the TFTP boot server with the console power saver disabled.

default profiles/castor/kernel
append initrd=profiles/castor/fsimage consoleblank=0 ramdisk_size=160000 root=/dev/ram0 
	castor_cfg=http://172.16.1.200/castor/cfg-list.txt

USB Boot Loader Example

This is a section of the syslinux.cfg contained in the root directory on the USB flash drive with the console power savings disabled.

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