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| [[Cortex | ''Click here to go back to the main Cortex article'']].
| | ''Obsolete page, please delete me.'' |
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| This page explains the setup of this cluster in detail.
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| == Network setup ==
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| === Connectivity ===
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| Cortex machines are connected to Cortex Switch, that links to VisLab switch with a fiber optic connection of 4Gbit/s.
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| === Cortex nodes ===
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| Cortex server and clients have the following IPs and domain names:
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| * Server: 10.10.1.240, server.visnet
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| * Client 1: 10.10.1.1, cortex1.visnet
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| * Client 2: 10.10.1.2, cortex2.visnet
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| * Client 3: 10.10.1.3, cortex3.visnet
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| * Client 4: 10.10.1.4, cortex4.visnet
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| * Client 5: 10.10.1.5, cortex5.visnet
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| * Client 6: 10.10.1.6, cortex6.visnet
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| ''For further details, see [[VisLab network]].''
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| == Boot procedure ==
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| The clients boot via the network, using the PXE system. Each machine determines its own identity and asks the server for a kernel image and an initial ram disk. Kernel images and initial ram disks are stored on the server in the <code>/tftpboot/</code> directory. Kernels can be stock kernels, but the initial ram disk must be created in a way that enables booting from the network. This is not as bad as it sounds. It involves invoking the command <code>mkinitramfs</code>.
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| The server decides which kernel and initramdisk to send to each machine based on the information stored in the two files: <code>/tftpboot/pxelinux.cfg/default</code>(for cortexes 1-5) and <code>/tftpboot/pxelinux.cfg/01-00-19-d1-9e-e9-53</code> (for cortex6).
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| The roots and the homes of the users are also stored on the server machine, so they are mounted by each client at boot time.
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| === Mounting of root directory ===
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| We are not sure which mechanism mounts the root filesystem, exactly. Here is the relevant line from <code>/etc/fstab</code>:
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| # <file system> <mount point> <type> <options> <dump> <pass>
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| /dev/nfs / nfs defaults 1 1
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| === Mounting of home directory ===
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| The home directory is mounted via the Upstart system a few seconds after booting. When rebooting the system, it is possible to login while <code>/home</code> is still not mounted. In that case, log out and log in again, in order for your environment variables to be set correctly.
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| In November 2010, we created a file called <code>/etc/init/mountHome-net.conf</code> containing:
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| description "Mount network filesystems"
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| start on started networking or runlevel 2
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| exec /usr/local/bin/mountHome.sh
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| and <code>/usr/local/bin/mountHome.sh</code> containing:
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| MOUNTED=$(mount | grep home)
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| while [ -z "$MOUNTED" ]
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| do
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| su icub -c 'mount /home' &> /var/tmp/mountHomeUpstartOut.txt
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| MOUNTED=$(mount | grep home)
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| echo $MOUNTED
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| sleep 1
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| done
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| ls /home > /var/tmp/mountHomeUpstartLs.txt
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| runlevel > /var/tmp/mountHomeUpstartRunlevel.txt
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| After a successful mount, we should see something like
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| $ mount | grep home
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| 10.10.1.240:/nfsroot.home on /home type nfs (rw,user=icub,addr=10.10.1.240)
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| If <code>/home</code> is wrongly mounted with the <code>noexec</code> flag, users won't be able to execute binaries located inside it.
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| == Server machine ==
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| The server has:
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| * a boot folder for the clients at <code>/tftpboot/pxelinux.cfg</code>. It contains the files:
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| ** <code>default</code> - default boot file;
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| ** <mac_address> - specific for a machine with the given mac address.
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| * startup scripts for each machine at <code>/nfsroot/app</code>
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| == Client machines ==
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| The clients have:
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| * A superuser account (<code>compurack</code>) to administer system-wide settings (configurations, libraries, etc.)
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| * Normal user accounts. By default, the login script runs the contents of file <code>$HOME/.bash_env</code>, where users can set their environment variables, e.g., <code>export ICUB_ROOT=$HOME/iCub</code>. This works for both interactive shell sessions and non-interactive ones (i.e., commands remotely invoked by <code>yarprun</code>).
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| * A <code>yarp</code> account to update and install the YARP library. Variable <code>YARP_ROOT</code> is set by default to <code>/home/yarp/yarp2</code> for all users (in <code>/etc/bash.bashrc</code>) <-- change this policy
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| * An <code>icub</code> account with sudo privileges (created with <code>sudo adduser icub admin</code> on 2009-06-30) <-- change this policy
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| * cortex6's <code>/etc/hosts</code> file can include the following line:
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| 127.0.0.1 cortex6
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