IBM LoadLeveler for AIX 5L: Using and Administering

Understanding striping

For a job to successfully run using the striped adapter method, there must be a common communication path among the nodes and adapters on the system. This communication path between different nodes and adapters is called the communication fabric.
View figure.
Consider these sample scenarios using the network configuration as indicated in the preceding figure:

• If a three node job requests a striped adapter, it will be dispatched to Node 1, Node 2 and Node 4 where it can communicate on Network B. It cannot run on Node 3 because that node only has a common communication path with Node 2, namely Network A.
• If a three node job requests css0, it will not be run because there are not enough connected adapters on css0 to run the job. Notice both adapter A on Node1 and adapter A on Node 4 are both at fault.
• If a three node job requests striped IP and some but not all of the nodes have multi-linked addresses, the job will only be dispatched to the nodes that have the multi-link addresses.

As you can see from these scenarios, LoadLeveler will find enough nodes on the same fabric to run the job. If enough nodes in the fabric cannot be found, no communication can take place and the job will not run.