Revision as of 16:57, 2 May 2010

HCL Nodes will be installed from a clone of a root node, hcl07. The general installation of the root is documented here. There are a number of complications as a result of the cloning process. Solutions to these complications are also explained.

General Installation

Partition filesystem with swap at the end of the disk, size 1GB, equal to maximum of the installed memory on cluster nodes. Root file system occupies the remainder of the disk, EXT4 format.

Install long list of packages.

Networking

Configure network interface as follows:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo eth0 eth1

iface lo inet loopback

# The primary network interface
allow-hotplug eth0
iface eth0 inet dhcp

allow-hotplug eth1
iface eth1 inet dhcp

Routing Tables

Add an executable script named 00routes to the directory /etc/network/if-up.d. This script will be called after the interfaces listed as auto are brought up on boot (or networking service restart). Note: the DHCP process for eth1 is backgrounded so that the startup of other services can continue. Our routing script adds routes on this interface even though it is not yet fully up. The script outputs some errors but the routing entries remain none-the-less. The script should read as follows:

#!/bin/sh

# Static Routes

# route ganglia broadcast t
route add -host 239.2.11.72 dev eth0

# all traffic to heterogeneous gate goes through eth0
route add -host 192.168.20.254 dev eth0

# all subnet traffic goes through specific interface
route add -net 192.168.20.0 netmask 255.255.255.0 dev eth0
route add -net 192.168.21.0 netmask 255.255.255.0 dev eth1

The naming of the script is important, we want our routes in place before other scripts in the /etc/network/if-up.d directory are executed, the order in which they are executed is alphabetical.

Hosts

Change the hosts file so that it does not list the node's hostname, otherwise this would confuse nodes that are cloned from this image.

127.0.0.1       localhost

# The following lines are desirable for IPv6 capable hosts
::1     localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

Ganglia

Install the ganglia-monitor package.

Configure ganglia monitor by editing /etc/ganglia/gmond.conf so that it contains:

cluster {
  name = "HCL Cluster"
  owner = "University College Dublin"
  latlong = "unspecified"
  url = "http://hcl.ucd.ie/"
}

And ...

/* Feel free to specify as many udp_send_channels as you like.  Gmond
   used to only support having a single channel */
udp_send_channel {
  mcast_join = 239.2.11.72
  port = 8649
  ttl = 1
}

/* You can specify as many udp_recv_channels as you like as well. */
udp_recv_channel {
  mcast_join = 239.2.11.72
  port = 8649
  bind = 239.2.11.72
}

After all packages are complete execute:

service ganglia-monitor restart

NIS Client

Install nis package. Set /etc/defaultdomain to contain heterogeneous.ucd.ie Make sure the NIS Server has an entry in /etc/hosts, this is because DNS may not be active when the NIS client is starting and we want to ensure that it connects to the server successful.

192.168.21.254   heterogeneous.ucd.ie heterogeneous

Make sure the file /etc/nsswitch.conf contains:

passwd:         compat
group:          compat
shadow:         compat

Append to the file: /etc/passwd the line +:::::: Append to the file: /etc/group the line +::: Append to the file: /etc/shadow the line +:::::::: Start the nis service:

service nis start

Check that nis is operating correctly by running the following command:

ypcat passwd

NFS

Add the line

192.168.21.3:/home	/home			nfs	soft,retrans=6		0 0

to /etc/fstab

NTP

Install NTP software:

apt-get install ntp

Edit configuration and make server heterogeneous.ucd.ie the sole server entry. Comment out any other servers. Restart the NTP service.

Complications

Hostnames

Debian does not pull the hostname from the DHCP Server. Without intervention cloned nodes will keep the hostname stored on the image of the root node. A bug describing the setting of a hostname via DHCP is described here

The solution we will use is to add the file /etc/dhcp3/dhclient-exit-hooks.d/hostname with the contents:

if [[ -n $new_host_name ]]; then
  echo "$new_host_name" > /etc/hostname
  /bin/hostname $new_host_name
fi

The effect of this is to set the hostname of the machine after an interface is configured using dhclient (DHCP Client). Note, the hostname of the machine will be set by the last interface that is configured via DHCP, in the current configuration that will be eth0. If an interface is reconfigured using dhclient, the hostname will be reset to the name belonging to that interface.

Further, the current hostnames for the second interface on nodes eth1 are invalid. They follow the format hcl??_eth1.ucd.ie, however the '_' character is not permitted in hostnames and attempting to set such a hostname fails.

udev and Network Interfaces

The udev system attempts to keep network interface names consistent regardless of changing hardware. This may be useful for laptops with wirless cards that a plugged in and out, but it causes problems when trying to install our root node image across all machines in the cluster. A description of the problem can be read here.

The solution is to remove the udev rules for persistent network interfaces, and disable the generator script for these rules. On the root cloning node do the following

1. remove the file /etc/udev/rules.d/70-persistent-net.rules
2. and to the top of the file: /lib/udev/rules.d/75-persistent-net-generator.rules, the following lines:

# skip generation of persistent network interfaces
ACTION=="*",                            GOTO="persistent_net_generator_end"