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# 5.1. Easy Configuration

The auto-discovery daemon (omdiscd) provides a way to automatically configure an openMosix cluster hence eliminating the need of a /etc/mosix.map or similar manual configurations. Auto-discovery uses multicast packages to notify other nodes that it is an openMosix node. This way adding an extra node to your mosix cluster means that you just have to start the omdiscd on your machine and it will join the cluster.

However there are some small requirements, Like with any openMosix cluster , you need to have networking configured correctly. mainly the routing. Without a default route, you must specify an interface to omdiscd with the -i option. Otherwise omdiscd will exit with an error like.

    Aug 31 20:41:49 localhost omdiscd[1290]: Unable to determine address of
    default interface.  This may happen because there is no default route
    configured.  Without a default route, an interface must be: Network is
    unreachable
    Aug 31 20:41:49 localhost omdiscd[1290]: Unable to initialize network.
    Exiting.

An example of a correct routing is below

    [root@localhost log]# route -n
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    10.0.0.0        0.0.0.0         255.0.0.0       U     0      0        0 eth0
    127.0.0.0       0.0.0.0         255.0.0.0       U     0      0        0 lo
    0.0.0.0         10.0.0.99       0.0.0.0         UG    0      0        0 eth0

Basically from now on everything will get easier. Just start

    omdiscd

And have a look at your logfiles you should see something similar to this

    Sep  2 10:00:49 oscar0 kernel: openMosix configuration changed: This is openMosix #2780 (of 6 configured)
    Sep  2 10:00:49 oscar0 kernel: openMosix #2780 is at IP address 192.168.10.220
    Sep  2 10:00:49 oscar0 kernel: openMosix #2638 is at IP address 192.168.10.78
    Sep  2 10:00:49 oscar0 kernel: openMosix #2646 is at IP address 192.168.10.86
    Sep  2 10:00:49 oscar0 kernel: openMosix #2627 is at IP address 192.168.10.67
    Sep  2 10:00:49 oscar0 kernel: openMosix #2634 is at IP address 192.168.10.74

Congratulations , your openMosix cluster is now working.

omdiscd has some other options that you can use. You can either run omdiscd as a daemon (default) or in the foreground where output goes to the screen (standard output) omdiscd -n . An interface can be specified with the -i option.

Now lets still have a short look at the other tool , it's showmap. This tool will show you the newly auto generated openMosix map.

    [root@oscar0 root]# showmap
    My Node-Id: 0x0adc

    Base Node-Id Address          Count
    ------------ ---------------- -----
    0x0adc       192.168.10.220   1
    0x0a4e       192.168.10.78    1
    0x0a56       192.168.10.86    1
    0x0a43       192.168.10.67    1
    0x0a4a       192.168.10.74    1

Auto-discovery has some other features not listed here such as a routing mechanism for clusters with more than one network. More detailed information can be found in the README and DESIGN files in the user-land tools source tree.

More recent versions of the openMosix rc scripts will first verify wether an /etc/openmosix.map file or similar exists before trying to use autoconfiguration.

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