System information

7.1 Complex Tasks

of the new cluster nodes have to be written to a mapping list. Hence, the node mapping

of hundreds of computer nodes is very time consuming. The situation will get worse if the

node has more than one Ethernet interface. The front end processor nodes of the HLT have

three Ethernet ports, for example.

To ease network setup, the HLT at CERN uses the CHARM to identify the node. Instead

of making a mapping between the host network interfaces and the logical node, the mapping

is made between the CHARM card and the logical node. This approach has a couple of

advantages, as for example:

• The MAC addresses of the CHARM diﬀers only in the least two signiﬁcant bytes.

This factor accelerates the assignment of the node.

• The MAC address is printed on the card bracket.

• The CHARM card has only one network interface and therefore there is only one entry

in the initial node name mapping list.

However, the MAC address of the nodes has to be added to the mapping list. This

process is also done automatically with the aid of the CHARM. A script running on the

CHARM starts a KNOPPIX live system on the host computer and with the aid of the

crsh.sh program, the ifconﬁg

command is executed on the host computer (section 7.1.1

explains the crsh.sh program). Following the part of the shell script which enters the MAC

address of the host system to the LDAP server:

# Get the Ethernet MAC of the host system

crsh.sh "ifconfig -a | grep HWaddr" > hostmac.txt

# Extract MAC address from file

hwaddr=$(more hostmac.txt | sed -e "s/.*HWaddr \$[0-9A-F:]*\$/\1/")

# Enter MAC to the LDAP server

param="hostname=$hostname&hwaddr=$hwaddr"

wget -O tempfile.txt ${LDAP-WEBURL}?$param

In this script, the Ethernet MAC addresses of the host system are obtained via the

ifconﬁg program. Next, the MAC address is extracted from the ifconﬁg output via sed

The LDAP server computer provides a web server to perform LDAP queries. The wget

program transmits the LDAP entry to the LDAP web server. The host name of the MAC

address is obtained by the name of the CHARM card. Thereby, the host name of a CHARM

card is the host name of the related node and an additionally suﬃx "-charm". The CHARM

installed in the node "feptpcao00" would be named, for example, "feptpcao00-charm".

ifconﬁg is used to conﬁgure network interface parameters on a Linux system.

sed is a non interactive stream orientated editor.

wget is a non-interactive network downloader.