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Managing Ensembles. Nilesh M. Bhide. System Access Models. The Stand-alone System Beowulf system unattached to any external network The Universally Accessible Machine Every node is accessible from the entire Internet The Guarded Beowulf A single front-end (“worldly node”). Assigning Names.
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Managing Ensembles Nilesh M. Bhide
System Access Models • The Stand-alone System • Beowulf system unattached to any external network • The Universally Accessible Machine • Every node is accessible from the entire Internet • The Guarded Beowulf • A single front-end (“worldly node”)
Assigning Names • Internal host names of the format • <cluster-letter><node-number> • Reserved IP addresses • 10.0.0.0 - 10.255.255.255 • 172.16.0.0 - 172.31.255.255 • 192.168.0.0 - 192.168.255.255 • Dynamically assigned Address • DHCP, BOOTP
Cloning Nodes • Configure one internal node and clone rest of them • Advantages • Quick and easy configuration of internal nodes • Facilitates major system upgrades • Easy recovery from disk failures, accidental file system corruption
Cloning Nodes (contd.) • Steps involved • Manual configuration of a single internal node • Install NFS automounter • Creation of tar images for each partition • omit /proc, which is not a physical disk partition • tar zclf /worldly/nfsroot/partition-name.tgz .
Cloning Nodes (contd.) • Setting up a clone root partition • Create a root directory for cloning on the worldly node. This should we exported via NFS • This directory should contain bin, dev, etc, lib, mnt, proc, sbin, tmp subdirectories • tar -C / -c -f - dev | tar xf - • tmp and etc subdirectories should be empty • etc/fstab enrty : “none /proc proc default 0 0” • Replace NFS root sbin/init script • Export NFS root directory
Cloning Nodes (contd.) • Setting up BOOTP • set up /etc/bootptab file .default:\ :sm=255.255.255.0:\ :ht=ether:\ :gw=192.168.1.1\ :rp=/export/nfsroot/: b002:ip=192.168.1.2:ha=0080c8638a2c=.default b003:ip=192.168.1.3:ha=0080c86359d9=.default • Enable bootpd daemon on the worldly node • /etc/inetd.conf
Cloning Nodes (contd.) • Building a boot clone floppy • CACR Beowulf cloning software • http://www.cacr.caltech.edu/beowulf • Building NFSROOT kernel • /usr/src/linux • mknod /dev/nfsroot b 0 255 • rdev zImage /dev/nfsroot • dd if=zImage of=/dev/fd0 bs=512
Basic System Administration • Booting and Shutting Down • /sbin/shutdown -h now (using prsh) • ATX power supplies • /sbin/shutdown -p now • The node file system • / :The root partition, containig system configuration and log files • /boot : An optional partition for storing kernel images
Basic System Administration • /home : A partition containing all user directories • /opt : An optional partition for additional software • /usr : A partition containing all standard system software • /scratch : A partition used as scratch space for large temporary data files
Basic System Administration • Account Management • NIS, NIS+ • useradd, adduser, linuxconf • Replicating /etc/passwd, /etc/group • NIS vs. Replication
Basic System Administration • PRSH - Parallel Remote Shell • http://www.cacr.caltech.edu/beowulf/. • e.g., prsh -- killall amok
Security Strategies • CERT: http://www.cert.org • System Configuration • Stand-alone, Universally accessible, Guarded • IP Masquerading • NAT (Network Address Translation) • Client node set up • route add default gw 192.168.1.1 • or /etc/sysconfig/network configuration (GATEWAY, GATEWAYDEV)
Security Strategies (Contd.) • Worldly node set up • IP Masquerade HOWTO in /usr/doc/HOWTO/mini • FORWARD_IPV4=true in /etc/sysconfig/network • Configure IP masquerading rules using ipfwadm • ipfwadm -F -p deny • ipfwadm -F -a masq -S 192.168.1.0/24 -D 0.0.0.0/0 • /etc/rc.d/rc.localor/etc/rc.d/init.d • ipfwadm-wrapper for 2.2 Linux kernels
Security Strategies (Contd.) • Restricting host access • TCP wrappers package • tcpd daemon invoked by inetd and listed in /etc/inetd.conf • /etc/hosts.deny and /etc/hosts.allow e.g., in.rshd: 10.0.0.0/255.255.255.0 • Placing worldly node behind firewall • SSH: http://www.ssh.fi/
Job Scheduling • Keeps user-developed applications from interfering with each other. • Currently no standard exists for job schedulers • BPROC (Beowulf Distributed Process Space) • http://www.beowulf.org/software/bproc.html