12.3. I don't see all my nodes

First of all , are you using the same kernel version on each machine ? The 'same-kernel' refers to the version. You can build different kernel images of the same source version to meet the hardware/software needs of a given node. However you wil need toe make sure that when you install openMosix on your cluster, all your machines should have the openmosix-x.x.x-y kernel installed, in contrast to having one machine running openmosix-x.x.z-x, another running openmosix-x.x.x-y, another running openmosix x.x.x-z, and so on and so forth

When you run mosmon, press t to see the total of machines running. Does it warn you that mosix is not running?

If yes, then make sure your machine's ip is included in /etc/mosix.map (don't use - if your machine's ip is such, then you probably have problems with your dhcp server/nameserver). If it does not tell you that mosix is not running, see what machines show up. Do you see only your machine?

If yes, then your machine is most likely running a firewall and is not letting openmosix through.

If not, then the problem is most likely with the machine that doesn't show up. Also: Do you have two nic cards on a node? then you have to edit the /etc/hosts file to have a line that has the following format

non-cluster_ip  cluster-hostname.cluster-domain cluster-hostname
Or you can supply a -p option to the setpe script to point to the openmosix id of the node it shoud recognise as "self". For example if your internal cluster IP of the master node is "cnode1", you might have an openmosix.map file like
1 cnode1 	1
2 cnode2     	1 
in which case the setpe script needs to be invoked with "setpe -p1 ...". In the same case the /etc/hosts file might read localhost
123.456.7.89 usual.name.domain nickname cnode1 cnode2
setpe -p1 -f /etc/openmosix.map 
will give you what you want. You may wish to edit the openmosix init script to do this properly.

You might also need to set up a routing table, which is a whole different subject.

Maybe you used different kernel-parameters on each machine? Especially if you use the 'Support clusters with a complex network topology' option you should take care that you use the same value for the also appearing option 'Maximum network-topology complexity support' on each machine.