A partition profile is a record on the Hardware Management Console (HMC) that specifies a possible configuration for a logical partition. When you activate a partition profile, the managed system attempts to start the logical partition using the configuration information in the partition profile. This topic includes a flash demo that shows an example scenario of creating partition profiles on server hardware.
A partition profile specifies the desired system resources for the logical partition and the minimum and maximum amounts of system resources that the logical partition can have. The system resources specified within a partition profile includes processors, memory, and I/O resources. The partition profile can also specify certain operating settings for the logical partition. For example, you can set a partition profile so that, when the partition profile is activated, the logical partition is set to start automatically the next time that you power on the managed system.
Each logical partition on a managed system that is managed by an HMC has at least one partition profile. If desired, you can create additional partition profiles with different resource specifications for your logical partition. If you create multiple partition profiles, you can designate any partition profile on the logical partition to be the default partition profile. The HMC activates the default profile if you do not select a specific partition profile to be activated. Only one partition profile can be active at one time. To activate another partition profile for a logical partition, you must shut down the logical partition before you activate the other partition profile.
A partition profile is identified by partition ID and profile name. Partition IDs are whole numbers used to identify each logical partition that you create on a managed system, and profile names identify the partition profiles that you create for each logical partition. Each partition profile on a logical partition must have a unique profile name, but you can use a profile name for different logical partitions on a single managed system. For example, logical partition 1 cannot have more than one partition profile with a profile name of normal, but you can create a normal partition profile for each logical partition on the managed system.
When you create a partition profile, the HMC shows you all of the resources available on your system. The HMC does not verify if another partition profile is currently using a portion of these resources. Therefore, it is possible for you to overcommit resources. When you activate a profile, the system attempts to allocate the resources that you assigned to the profile. If you have overcommitted resources, the partition profile will not be activated.
For example, you have four processors on your managed system. Partition 1 profile A has three processors, and partition 2 profile B has two processors. If you attempt to activate both of these partition profiles at the same time, partition 2 profile B will fail to activate because you have overcommitted processor resources.
When you shut down a logical partition and reactivate the logical partition using a partition profile, the partition profile overlays the resource specifications of the logical partition with the resource specifications in the partition profile. Any resource changes that you made to the logical partition using dynamic logical partitioning are lost when you reactivate the logical partition using a partition profile. This is desirable when you want to undo dynamic logical partitioning changes to the logical partition. However, this is not desirable if you want to reactivate the logical partition using the resource specifications that the logical partition had when you shut down the managed system. It is therefore best to keep your partition profiles up to date with the latest resource specifications. You can save the current configuration of the logical partition as a partition profile. This allows you to avoid having to change partition profiles manually. For more information about this procedure, see Saving the partition configuration to a partition profile.
If you shut down a logical partition whose partition profiles are not up to date, and the logical partition is set to start automatically when the managed system starts, you can preserve the resource specifications on that logical partition by restarting the entire managed system using the partition autostart power-on mode. When the logical partitions start automatically, the logical partitions have the resource specifications that the logical partitions had when you shut down the managed system.
The following Flash demo explains how
partition profiles are used. The following Flash demo requires the Flash plug-in. 
Alternatively, you can use the HTML version of this demo.
Memory and processor resource assignment
When you create a partition profile for a logical partition, you set up the desired, minimum, and maximum amounts of memory and processor resources that you want for the logical partition. (Where applicable, this also applies to 5250 CPW.) The desired value is the resource amount that the logical partition gets if you do not overcommit the resource on the managed system. If the desired amount of resources is available when you activate the partition profile, then the logical partition starts with the desired amount of resources. However, if the desired amount of resources is not available when you activate the partition profile, then the resources on your managed system are overcommitted. In that case, if the amount of resources that are available on the managed system is equal to or greater than the minimum amount of resources in the partition profile, then the logical partition starts with the available amount of resources. If the minimum amount of resources is not met, then the logical partition does not start.
Virtual processor assignment
- The default minimum number of virtual processors is the minimum number of processing units (rounded up to the next whole number). For example, if the minimum number of processing units is 0.8, the default minimum number of virtual processors is 1.
- The default desired number of virtual processors is the desired number of processing units (rounded up to the next whole number). For example, if the desired number of processing units is 2.8, the default desired number of virtual processors is 3.
- The default maximum number of virtual processors is the maximum number of processing units rounded up to the next whole number and multiplied by two. For example, if the maximum number of processing units is 3.2, the default maximum number of virtual processors is 8 (4 times 2).
When you activate the logical partition using the partition profile on the HMC, the logical partition is assigned the desired number of virtual processors. You can then use dynamic logical partitioning to change the number of virtual processors to any number between the minimum and maximum values, so long as the number of virtual processors is greater than the number of processing units that are assigned to the logical partition. Before changing the default settings, performance modeling should be performed.
- Minimum processing units 1.25
- Desired processing units 3.80
- Maximum processing units 5.00
- Minimum virtual processors 2
- Desired virtual processors 4
- Maximum virtual processors 10
When you activate the logical partition using this partition profile on the HMC, the operating system sees four processors, because the logical partition is activated with the desired value of four virtual processors. Each of these virtual processors has 0.95 processing units supporting the work assigned to the processor. After the logical partition is activated, you can use dynamic logical partitioning to change the number of virtual processors on the logical partition to any number between 2 and 10, so long as the number of virtual processors is greater than the number of processing units that are assigned to the logical partition. If you increase the number of virtual processors, bear in mind that you will have less processing power supporting the work assigned to each processor.
I/O device assignment
- If an I/O device is assigned to a partition profile as required, then the partition profile cannot be successfully activated if the I/O device is unavailable or is in use by another logical partition. Also, after the logical partition starts, you cannot use dynamic logical partitioning to remove the required I/O device from the running logical partition or move the required I/O device to another logical partition. You must shut down the logical partition before the I/O device can be used by another logical partition. This setting is suitable for devices that are required for the continuous operation of the logical partition (such as disk drives).
- If an I/O device is assigned to a partition profile as desired, then the partition profile can be successfully activated if the I/O device is unavailable or is in use by another logical partition. The desired I/O device can also be removed from the running logical partition or moved to another logical partition using dynamic logical partitioning. This setting is suitable for devices that you want to share among multiple logical partitions (such as optical drives or tape drives).
The exception to this rule is InfiniBand (IB) adapters, which are always added to partition profiles on the HMC as required. Each physical InfiniBand (IB) adapter contains a set of 64 globally unique IDs (GUIDs) that can be assigned to partition profiles. You can assign multiple GUIDs to each partition profile, but you can assign only one GUID from each physical InfiniBand (IB) adapter to each partition profile. Also, each GUID can be used by only one logical partition at a time. You can create multiple partition profiles with the same GUID, but only one of those partition profiles can be activated at a time.
If you create an i5/OS® logical partition using the HMC, you must tag I/O devices to perform certain functions for that i5/OS logical partition. For more information on these types of devices, see Tagged resources for i5/OS logical partitions.