View figure.
System partitioning is supported by the SP software in the ssp.top install file set. You can choose to install this support when you install PSSP on the control workstation. This provides the system with a directory of predefined system partitioning layouts, as well as the System Partitioning Aid, a tool for building additional layouts. The directory is represented in Figure 36. An introduction to the System Partitioning Aid is provided in Appendix A, The System Partitioning Aid - A brief tutorial.
For system partitioning purposes, a system is cataloged by its switch configuration. The number of used node slots in the system and the type of nodes the system contains play a role in how you want to partition your system. However, the quantity and kinds of switches determine your options.
A switch board to which nodes are connected is called a Node Switch Board (NSB). In larger systems, it becomes impossible to adequately connect all pairs of NSBs to each other. Additional switch boards are inserted to provide additional connectivity. These extra switch boards have no nodes attached, just other switch boards. Such a switch board is called an Intermediate Switch Board (ISB).
For example, the 1-frame system considered in Example 1 is classified as a 1nsb0isb system. It has 1 NSB and 0 ISBs. The system of Example 3 had 3 frames, but only 2 switch boards. It is a 2nsb0isb system.
The syspar_configs directory within the spdata file system contains all system partition configuration information. Figure 36 shows this directory structure. In this figure, subdirectory 2nsb0isb is expanded to illustrate the predefined layouts available for such systems:
Example 3 - An SP with 3 frames, 2 SP Switches, and various node sizes illustrates how to construct a new 8_8_16 layout. You could use the System Partitioning Aid to save this layout, in which case, the System Partitioning Aid would introduce a corresponding new config.8_8_16 directory in the 2nsb0isb subtree. Within that new config-level directory, a layout subdirectory would be introduced named layout.name_desired where name_desired is a name you specified to the System Partitioning Aid.
Example 2 - A switchless system illustrates (implicitly) how to construct a new, switchless 4_12 layout. Although only 7 nodes were available, you had a full frame for which the maximum size system is 16; categorization is based on the maximum number of nodes and any unlisted nodes go in the last partition. If you use the System Partitioning Aid to save this layout, the System Partitioning Aid would save it in the 1nsb0isb subtree as 1nsb0isb/config.4_12/layout/layout.name_desired where name_desired is a name you specify to the System Partitioning Aid.
Figure 36. The directory structure of system partition information
View figure.
The higher-level directories descriptions, sysparlists, nodelists, and topologies contain the files common to various configuration layouts. For predefined layouts, the low-level files layout.desc, nodes.syspar, nodelist, and topology are actually links into these higher-level directories. For layouts constructed via the System Partitioning Aid, no links are used; the actual files are stored at these lower levels.
The specifics of each of the predefined configurations are in Appendix B, "System Partitioning". Consult that information as you complete the worksheets in Appendix C, SP system planning worksheets.