Managing an openMosix Cluster

The administrator can configure and tune the openMosix-cluster by using the openMosix-user-space-tools or the /proc/hpc interface.

The values in the flat files in the /proc/hpc/admin directory present the current configuration of the cluster. Hence the administrator can write its own values into these files to change the configuration during runtime, e.g.

echo 1 > /proc/hpc/admin/block

locks the arrival of remote processes

echo 1 > /proc/hpc/admin/bring

...

Next to changing values you can also get more information about your cluster from this interface.

cat /proc/hpc/nodes/[openMosix_ID]/CPUs 

cat /proc/hpc/nodes/[openMosix_ID]/load

Within the /proc/$PID/ subsystem you can find important information about the status of a process, whether it locked (/proc/$PID/lock) or sent to another node (/proc/$PID/where) , or even why that specific process can't move to another node (/proc/$PID/cantmove) , how many times it has been migrated (/proc/$PID/migrate)

As we will see later on, there are also graphical user interfaces that can be used to see or modify these values, but in a scripted environment the ones mentioned above may come in handy !

We also have a bunch of command line tools that provide easy administration to openMosix clusters. migrate [PID] [openMosix_ID] sends the process $PID to openmosix node $openMosix_ID. mon is a ncurses-based terminal monitor: important information about the current status is displayed in bar-charts.

The main openMosix configuration utility is mosctl, with this tool you can define wether processes should stay or leave the current node, you can set a new speed for a certain node, you can ask migrated processes to come home again and provides much other features that are documented in the HOWTO.

mosrun can be used to run a special configured command on a chosen node

mosrun  [-h|openMosix_ID| list_of_openMosix_IDs] command [arguments]

The mosrun command can be executed with several more command line options. To ease this up there are several preconfigured run-scripts for executing jobs with a special (openMosix) configuration.

Last but not least there is the setpe tool. It is required for the configuration of a node. It is used to enable or disable openmosix on a node (setpe -f /etc/openmosix.map or setpe -off)

Additional to the /proc interface and the command line-openMosix utilities (which are using the /proc interface) there is a patched "ps" and "top" available (they are called "mps" and "mtop") which display also the openMosix-node ID column wise . This is useful for finding out where a specific process is currently being computed.

Apart from using the command line interfaces and fiddling with files in /proc the openMosix community has been contributing some interested tools that make maintaining an openMosix cluster a lot easier.

The most famous one is probably the openMosixView tool by Matthias Rechenburg, openMosixView aims at providing a very intuitive GUI for managing and monitoring an openMosix cluster. All of the most commonly used actions one wants to perform in an openMosix cluster have been implemented in a QT based user interface. openMosixView contains multiple parts.

openMosixview displays all important openMosix related information of each node as well as the overall cluster state in the main application window. All other components included in the openMosix application suite are directly accessible from this main GUI.

openMosixprocs gives an overview of wich process is running on which node It is a "top-like" process monitor that displays the openMosix-node ID of each process. 0 means local, all other values are remote nodes. Migrated processes are marked with a green icon and unmovable processes have a lock.

The openMosixanalyzer provides a non-stop openMosix-history of your cluster. It displays the log-files created by openMosixcollector in a graphically way The openMosixanalyzer can analyze the current "online" logfiles Older backups of your openMosixcollector history logs can be opened easily by the file menu.

openMosixhistory gives a detailed overview of which process was running on which node in the past . The openMosixcollector saves the process list from the host the collector was started. These historic-process logs are browsable with openMosixhistory.

The openMosixmigmon is a monitor for migrations in openMosix-clusters. It displays all nodes as little penguins sitting in a circle. The main penguin is the node on which openMosixmigmon runs and around this node it shows its processes also in a circle of small black squares.

If a process migrates to one of the nodes the node gets an own process-circle and the process moves from the main process-circle to the remote process-circle. Then the process is marked green and draws a line from its origin to its remote location to visualize the migration.

The openMosixmigmon is fully Drag'n Drop enabled. You can grab (drag) any process and drop them to any of your nodes (those penguins) and the process will move there. If you double-click a process on a remote node it will be send home immediately.

Next to openMosix view we have multiple smaller tools for either monitoring or managing a cluster. We have 3dmosmon , which is a nice 3D replacement for the text based Mon tool, the openMosixwebview tool by Ramons Pons and lots of other tools that are listed in the contribution page on the openMosix website.