Role

Each server in the cluster is called a node in CHESS and each node can be assigned to have one or more roles. We usually characterize a node based on their role. For example, a “management node” is one having the management role; an “execution node” with execution role; an “I/O node” with I/O role; and a “terminal node” with terminal role. Details of each role are shown as follows:

Management (M)

• Each cluster has one or two management nodes.
• A management node runs a set of system services and maintains the user database.
• A management node can also be with execution role. Though it is not recommended, it is fairly common for small cluster.
• A management node can act as I/O node. Again, it is better to have dedicated I/O nodes for bigger cluster.

Execution (E)

• Usually most of the nodes of a cluster are execution nodes.
• The execution nodes execute jobs submitted by users.

I/O (I)

• Usually there is one or more I/O nodes.
• The I/O nodes usually serve as NFS (Network File System) servers or servers of another parallel file system.

Terminal (T)

• There are end points that the users interact with the cluster, such as development and job submission.
• It is common to have the management node serves with terminal role.
• In bigger deployment, it is recommended to have dedicated nodes for the terminal role.