This chapter provides an overview of partitions and how a partitioned system is managed.
Partitioning your system is similar to partitioning a hard drive. When you partition a hard drive, you divide a single physical hard drive so that the operating system recognizes it as a number of separate logical hard drives. You have the option of dividing the system's resources by using the HMC to partition your system. On each of these divisions, called partitions, you can install an operating system and use each partition as you would a separate physical system.
The HMC allows you to use two types of partitions: logical partitions, and the Full System Partition.
Logical partitions are user-defined system resource divisions. Users determine the number of processors, memory, and I/O that a logical partition can have when active.
Some systems are equipped to use affinity partitions. An affinity partition is a special type of logical partition. Affinity partitions are divisions of system-defined resources that have a close physical proximity to each other. When you decide to create an affinity partition, the system determines the number of processors and memory that a partition can have, but the user determines the I/O requirements for each of these partitions.
A special partition called the Full System Partition assigns all of your managed system's resources to one large partition. The Full System Partition is similar to the traditional, non-partition method of operating a system. Because all resources are assigned to this partition, no other partitions can be started when the Full System Partition is running. Likewise, the Full System Partition cannot be started while other partitions are running.
The HMC allows you to easily switch from the Full System Partition to logical partitions. The actual setup of the operating system in a partition may require some careful planning to ensure no conflicts exist between the two environments.
Partitioning provides greater flexibility when deploying multiple workloads on servers, providing better management, improved availability, and more efficient use of resources.
Using the HMC to manage your pSeries partitioned system, different managed-object types exist within the user interface. You can perform management functions by selecting the appropriate object type and then selecting an appropriate task. The main types of objects are managed systems, partitions, and profiles.
Managed systems are the systems that are physically attached to and managed by the HMC. The HMC can perform tasks that affect the entire managed system, such as powering the system on and off. You can also create partitions and profiles within each managed system. These partitions and profiles define the way that you configure and operate your partitioned system.
Within your managed system, you can assign resources to create partitions. Each partition runs a specific instance of an operating system. The HMC can perform tasks on individual partitions. These tasks are similar to those you can perform on traditional, non-partitioned servers. For example, you can use the HMC to start the operating system and access the operating system console.
Because the HMC provides a virtual terminal for each partition, a terminal window can be opened for each console. This virtual terminal can be used for software installation, system diagnostics, and system outputs. The managed system firmware and device drivers provide the redirection of the data to the virtual terminal. For more information about the virtual terminal window, see Virtual Terminal Window.
A profile defines a configuration setup for a managed system or partition. The HMC allows you to create multiple profiles for each managed system or partition. You can then use the profiles you created to start a managed system or partition in a particular configuration.
You can create the following types of profiles:
When you activate a partition, you enable the system to create a partition using the set of resources in a profile created for that partition. For example, a logical partition profile might indicate to the managed system that its partition requires 3 processors, 2 gigabytes of memory, and I/O slots 6, 11 and 12 when activated.
You can have more than one profile for a partition. However, you can only activate a partition with one profile at a time. Additionally, affinity partitions and logical partitions cannot be active at the same time.
Partition profiles are not affected by changes you make using the Dynamic Logical Partitioning feature. If you want permanent changes, you must then reconfigure partition profiles manually. For example, if your partition profile specifies that you require two processors and you use Dynamic Logical Partitioning to add a processor to that partition, you must change the partition profile if you want the additional processor to be added to the partition the next time you use the profile.
The system profile helps you change the managed systems from one complete set of partitions configurations to another. For example, a company might want to switch from using 12 partitions to using only four, every day. To do this, the system administrator deactivates the 12 partitions and activates a different system profile, one specifying four partitions.
When you create a group of affinity partitions, the HMC automatically creates a system profile that includes all of the affinity partitions that you created.