Re: Linux Clusters

Hi Jack,

> We are setting up a Linux Cluster dedicated to 3D Data Visualization and/or
> powerpoint presentations:)
> My question is the status of the cluster code, any examples? We are using
> Redhat 7.3?

Excellent question, which has motivated me to clean up the
VisAD cluster work a bit and set up an example for you. The
idea is that data are distributed across the nodes (i.e.,
processors) of a cluster, with one file per node. These are
then visualized interactively on a user workstation.

Cluster nodes are generally not visible (in the sense of
Internet routes) from user workstations. Instead the nodes
are visible from a cluster host and the host is visible
from user workstations. So VisAD runs one Java command on
each cluster node, one command on the cluster host, and
one command on the user workstations. I haven't done anything
yet with automatically launching the commands on the cluster
nodes, but will be happy to work with you in setting that up
after you try our example.

Our example uses four files of output from the WRF model,
that should be installed on four cluster nodes. The files
are available from:

and are named:


You'll also need the latest untested VisAD from:

Note that the corresponding VisAD source is available from:

You'll need Java installed on all four cluster nodes, the cluster
host and the user workstation. Install the data files on the four
nodes and the new untested visad.jar on all machines. And make sure
rmiregistry is running on all these machines too.

Then run the following:

 On cluster node1:
   java -cp visad.jar visad.cluster.TestProxyCluster 1 wrfout_01_000000_0000

 On cluster node2:
   java -cp visad.jar visad.cluster.TestProxyCluster 2 wrfout_01_000000_0001

 On cluster node3:
   java -cp visad.jar visad.cluster.TestProxyCluster 3 wrfout_01_000000_0002

 On cluster node4:
   java -cp visad.jar visad.cluster.TestProxyCluster 4 wrfout_01_000000_0003

 Please ignore debug messages on cluster nodes, but . . .
 Wait for "data ready as ..." on all four cluster nodes.

 On cluster host:
   java -cp visad.jar visad.cluster.TestProxyCluster 0 node1 node2 node3 node4

 Wait for "data ready as ..." on cluster host.

 On user workstation:
   rmiregistry &
   java -cp visad.jar visad.cluster.TestProxyCluster 5 host

 When 3-D window pops up, click on "Maps".
 When maps window pops up, click on "Detect" and "Done".
 After "please wait ..." message in 3-D window goes off, click on "Widgets".
 When widgets window pops up, slide "RRP" slider over to about 0.003.
 When iso-surfaces appear, click "Go" to animate.

Note that 'node1', 'node2', 'node3' and 'node4' are the IP
names of the four cluster nodes, visible from the cluster
host. And 'host' is the IP name of the host.

The demo is essentially a SpreadSheet cell, applied to a
weather model output data set. It could be applied to other
kinds of data, with a little effort. We used a SpreadSheet
cell to test and demonstrate a wide range of VisAD interaction
modes with cluster data.

You will undoubtedly encounter problems. Please let me know
and we'll solve them together. I would be very happy to have
someone interested in working with this VisAD cluster code.

Bill Hibbard, SSEC, 1225 W. Dayton St., Madison, WI  53706
hibbard@xxxxxxxxxxxxxxxxx  608-263-4427  fax: 608-263-6738