Introduction to nPartitions

Hard Partitions (nPartitions) have dedicated hardware within an HP 9000 that work independently from other nPartitions within the same server. This independence includes both hardware and software isolation from other nPartitions. Virtual Partitions (vPars) covered in an Chapter 16 have full software isolation from one another. nPartitions have both software and hardware isolation from one another. An nPartition could be divided into multiple vPars.

The basic building block of an nPartition is the cell . Each cell has on it processors and memory that are assigned exclusively to that nPartition. I/O chassis are also exclusively assigned to nPartitions. Multiple cells can be combined to produce large nPartitions.

nPartitions are supported on many HP 9000s and operate in a similar manner on all models. I'll use a few different models in the examples in this chapter; however, the operation of nPartitions varies very little going from model to model, so most of the commands and principles apply regardless of the model on which you're using nPartitions.

Although the operation of nPartitions is nearly identical going from model to model, the number of supported nPartitions does indeed vary based on the cell capacity of a given model. Some models support only two nPartitions and others support many more. I'll focus on working with nPartitions in this chapter so you can use the topics covered on any cell-based system that supports nPartitions.

This chapter provides an introduction to working with nPartitions. There is a lot involved in managing nPartitions, so this chapter covers some of the more common nPartition- related work you might perform. For a complete guide to managing nPartitions please print the document HP System Partitions Guide: Administration for nPartitions , available on docs.hp.com. This document covers a lot more detail than is found in this chapter. Although nPartitions are supported on a number of HP 9000 platforms, there are some additional aspects of managing a Superdome complex (the overall system on which nPartitions run) that are covered in detail in Managing Superdome Complexes: A Guide for HP-UX System Administrators also found on docs.hp.com. There are many fine documents on this Web site related to many topics covered in this book that can help you in your work.

Cells and nPartitions

Since the cell is the basic building block of nPartitions, let's spend a little time covering some of the basics of cells and nPartitions. An HP 9000 that is capable of supporting nPartitions is sometimes called a server complex or just complex . In this chapter I sometimes use complex and other times use system when referring to the overall system. The following list covers some important background you'll need to know in order to manage nPartitions.

Base Cells	All cells within an nPartition are base cells. When you create an nPartition, the cells to which youassignitarebasecells.
Assigned Cells	Assigned cells are included in an nPartition and unassigned cells are not included. Similarly, an I/O chassis that is attached to a cell takes on the assigned or unassigned attribute of the cell.
Unassigned Cells	Cells that are unassigned are available resources that can be used to create new nPartitions or assigned to existing nPartitions.
Core Cells	Every nPartition must have a cell that is attached to an I/O chassis that has a core I/O card in it. You can have multiple core cells, meaning cells to which an I/O chassis is attached with a core I/O card in it, but only one of these is the active core cell. If you have multiple core cells in an nPartition and the primary core cell fails, then you have a backup core cell. Not all HP 9000s allow you to have multiple core cells.
Active Cells	Cells that are both assigned to an nPartition and have booted are active cells. There is the concept of rendezvous on HP 9000s. During the boot process an nPartition rendezvous takes place when all of the available cells in an nPartition join together. Those that rendezvous are active cells.
Inactive Cells	These are cells that are not assigned to an nPartition or have not yet rendezvoused to form a partition. Some cells are in a boot-is-blocked (BIB) state, which means that they will not rendezvous and are inactive. There are a variety of reasons that a cell is in a BIB state including: it is in an n state for the next boot; it boots too late to rendezvous; the cell fails a self-test; the partition in which the cell exists is ready for reconfiguration.
Genesis nPartition	The Genesis nPartition is a one-cell nPartition used to create all other nPartitions. It can be expanded to include any number of cells but is initially only one cell. This is done for you by HP when your nPartition-capable system is delivered, if you have requested it. You may create the genesis partition at any time and reconfigure your server with a new nPartition structure. The genesis nPartition is number 0. All cells in an nPartition must have the same clock speed and revision level.
Partition Numbers	Every nPartition has a unique number used by the commands and utilities to specify the nPartition.
Local Partition	When working with one of the commands or utilities, the nPartition you are accessing is local and all others are remote.

Now that we've covered some of the basics of nPartitions and cells, let's take a look at some of the tools and utilities used to manage them.

There are many supported nPartition configurations on all HP 9000s that support nPartitions. To see a complete list of the supported nPartition configurations see the aforementioned HP System Partitions Guide: Administration for nPartitions on docs.hp.com.

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