Creating an LPAR

A detailed guide on building Logical Partitions on IBM Power Systems

Key Highlights

Access and Navigation: Learn how to navigate the Hardware Management Console (HMC) or Integrated Virtualization Manager (IVM) to access your managed system.
Resource Allocation: Understand how to configure processor and memory resources by specifying minimum, desired, and maximum settings.
Multiple Methods: Explore various methods including a GUI-based approach, command-line instructions, and scripting (e.g., using the malt tool) for LPAR creation.

Introduction to Logical Partitions (LPARs)

A Logical Partition (LPAR) is a virtualized instance of a machine that allows you to run separate operating systems on a single physical IBM Power System. The LPAR technology facilitates resource allocation, software isolation, and the efficient use of hardware. By using an HMC, IVM, or even command-line tools, administrators can create, configure, and manage multiple LPARs to suit various workload requirements.

Methods for Creating an LPAR

There are several methods available for creating an LPAR. The most common are:

Using the Hardware Management Console (HMC) GUI

The HMC provides a graphical user interface that simplifies the process of LPAR creation. It is designed for ease of use, allowing operators to configure various parameters interactively.

Step 1: Access the HMC

Start by logging into your HMC with credentials that have the necessary permissions. Once logged in, navigate to the managed system where the LPAR will reside. This typically involves selecting the correct server from a list of available systems.

Step 2: Initiate LPAR Creation

In the HMC, select the option to create a new LPAR. This is often found in the "Configurations" or "Tasks" menu. In some setups, you may need to click “Create Partition” directly.

Step 3: Define Partition Details

In this step you will:

Specify the Partition Name: Enter a unique name for your LPAR to help identify it in the future.
Assign a Partition ID: Typically, the system auto-generates this ID, but some systems provide an option to specify a custom value.

Step 4: Configure Processor and Memory Resources

Allocate the primary resources needed for proper function:

Processor Settings: Configure three values:
- Minimum: The base amount of processing power required for the LPAR to boot.
- Desired: The optimal number when workloads increase.
- Maximum: The upper limit of processing ability, ensuring that the LPAR does not take more than its share of the system resources.
Memory Settings: Similar to processors, memory allocation involves:
- Minimum: Ensures the LPAR has sufficient RAM during startup.
- Desired: Reflects the typical operational memory usage.
- Maximum: Prevents the LPAR from consuming too much memory, potentially impacting other partitions.

Step 5: Assign Virtual Adapters

Virtual adapters provide network and storage connectivity:

Virtual Ethernet Adapters: Connect your LPAR to networks via virtual NICs.
Virtual SCSI Adapters: Link the LPAR to the appropriate logical volumes within a volume group (often separate from rootVG).

Step 6: Activate the LPAR

After finalizing the configurations, activate the LPAR. This process may start the operating system installation if it is a new partition.

Using the "malt" Scripting Tool

For administrators seeking automation and customization through scripting, the "malt" tool facilitates LPAR configuration without relying on a GUI. This tool is a suite of shell scripts and configuration files.

Setup and Configuration

Download the malt tool from the appropriate source and modify the configuration files to reflect your system’s requirements. This may include setting variables for LPAR name, processor allocation, memory sizes, and virtual adapter parameters.

Running the Script

Execute the malt script with all necessary parameters. The script will automatically create the LPAR, configure the requested resources, and add virtual adapter settings. This method is highly efficient when deploying multiple partitions or when integrating into a larger automation framework.

Using Command-Line Tools

For those who prefer command-line operations, IBM provides various commands that allow you to create and manage LPARs. This approach provides flexibility and precision, particularly for complex configurations.

Command: dpmlpar

One of the most widely used commands is dpmlpar image, which can create an LPAR and set out its resource parameters. Below is a basic example:


# Execute the following command to create an LPAR:
dpmlpar image -hmc <HMC_name> -lparname <LPAR_name> -min_memsize <min_memory> -desired_memsize <desired_memory> -max_memsize <max_memory> -proc_mode {shared|dedicated}

Replace placeholder variables with specific values to match your requirements.

Key Considerations

When using command-line tools, consider the following:

Parameters: Ensure all resource values—both processor and memory—are accurately described.
Operating System: After creating the partition, you may need to install the operating system if the LPAR is intended for new deployment.
Validation: Always validate configurations by checking partition status after execution of commands.

Resource Allocation Explained

An essential aspect of creating an LPAR is the proper allocation of both processing power and memory. This section examines the distinction between the minimum, desired, and maximum settings.

Processor Allocation

The processor settings are defined as follows:

Minimum Processors: The least number of processing units required to boot the LPAR. If the system cannot guarantee this minimum, the partition will not be started.
Desired Processors: This value is used during normal operations under ideal conditions. It represents the typical resource allocation for performance.
Maximum Processors: The ceiling of processing units that the LPAR is allowed to consume. This prevents resource overcommitment in a multi-partition environment.

Memory Allocation

Memory is allocated using a similar principle:

Minimum Memory: The lowest amount of RAM required to initialize the LPAR. Insufficient memory can lead to boot failure.
Desired Memory: Describes the amount of memory that the partition is expected to use during normal workload conditions.
Maximum Memory: Caps the memory usage of the LPAR and ensures that other partitions are not adversely affected by memory contention.

Additional Network and Storage Configurations

Beyond the allocation of processing resources, establishing connectivity through virtual adapters is a must. Here’s how you can configure network and storage:

Virtual Ethernet and SCSI Adapters

For a fully functional LPAR, you need to set up virtual network and storage connections:

Virtual Ethernet Adapters: Attach these to provide network connectivity. They allow the LPAR to interact with other systems on your network, and you can configure them similar to physical network interface cards.
Virtual SCSI Adapters: Assign a logical volume (typically from a volume group other than rootVG) to ensure that the LPAR has dedicated storage resources. Properly setting these up is crucial for disk I/O performance.

Table: LPAR Creation Options Overview

Method	Interface	Resource Configuration	Automation
HMC GUI	Graphical	Interactive setup for processor, memory, and adapters	Limited scripting
malt Scripting Tool	Command-Line/Scripts	Highly configurable through scripts	Fully automated deployment
Command-Line Tools	Terminal/CLI	Direct command execution with dpmlpar etc.	Scriptable for automation

Best Practices and Additional Tips

Pre-Planning and Resource Allocation

Before initiating the LPAR creation process, conduct thorough planning:

Assess Available Resources: Confirm that the managed system has sufficient spare processor cycles and memory. Avoid overallocation which might impact performance.
Define Clear Objectives: Understand the purpose of the LPAR – whether it’s for testing, production, or development – to determine the appropriate resource allocation.
Document Settings: Keep a record of the settings used (processor, memory, adapter configurations) for troubleshooting and future reference.

Validation and Testing

After creating your LPAR, always perform these steps:

Startup Validation: Ensure that the partition boots correctly by monitoring the HMC or CLI feedback.
Operational Testing: Verify that network connectivity, storage access, and processor performance meet the intended objectives. This may involve running benchmark tests.
Resource Monitoring: Use monitoring tools to track resource utilization over time to adjust settings if necessary.

Security Considerations

Security is integral to managing an LPAR:

Access Control: Maintain strict user authentication and permission settings on the HMC or the system creating the partition.
Patch Management: Regularly update software on both the physical and virtual environments to address vulnerabilities.
Network Isolation: Where possible, use Virtual LANs (VLANs) or other segmentation techniques to isolate LPAR traffic from sensitive or production environments.

Additional Automation and Troubleshooting Tools

Modern IT environments benefit greatly from automation. Beyond the basic methods:

Integrating LPAR Creation into Automation Frameworks

Many organizations tie LPAR creation into broader automation platforms:

Use API calls offered by the HMC in orchestration scripts to enable batch creation and management of multiple partitions.
Incorporate LPAR initialization into CI/CD pipelines to dynamically provision test environments.
Logging and error reporting within automated scripts can help quickly identify failures in resource allocation or configuration mismatches.

Common Pitfalls

Avoid these common mistakes when creating LPARs:

Overcommitting Resources: Allocating too many processors or too much memory to a single LPAR can starve other partitions.
Insufficient Validation: Failing to thoroughly test the partition after configuration may lead to unexpected downtimes.
Incorrect Adapter Assignment: Always double-check that virtual adapters are correctly configured, particularly in environments with stringent networking or storage policies.