Introduction: Make the most of hardware resources

This mini how-to shows you how to dual boot between AIX® and Linux® operating systems in a clustering environment, where available hardware resources are limited. The information presented in this document is based on actual experience. It should be used only by those who have some knowledge of system administration and skills in working with the IBM System p5™ (formerly pSeries®) architecture.

Scenario, prerequisites, requirements

There are situations when you need dual booting to make use of available hardware, or to use different operating systems to do performance analysis on certain devices. In the scenario explored here, we have an existing AIX cluster configured on IBM System p5 nodes with Federation and InfiniBand adapters to provide high-speed communications. The requirement calls for another cluster running Linux on POWER™ in which we prefer to use the InfiniBand adapters as part of the Linux configuration, since the Federation adapters are not recognizable on Linux and prevent booting. This document covers dual booting AIX and Linux in a clustering environment using IBM Cluster Systems Management (CSM) software. For a non-clustering environment, please refer to the previous developerWorks article, "Dual boot Linux and AIX," by Matt Davis (see Resources).

This particular AIX cluster has the minimum hardware and software installed and configured, as follows:

1. A single hardware management console (HMC)
2. One System p5 management server running AIX and CSM
3. 36 System p5 nodes with two internal hard drives (AIX installed on first hard drive) and Federation and InfiniBand adapters

Booting Linux using the existing hardware requires an additional System p5 management server. This management server is to be configured with Linux and CSM. Install Linux on the second management server, and then install and configure CSM by following the instructions in the CSM Planning and Installation Guide (see Resources).

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Preparing to dual boot AIX and Linux

The procedures outlined below assume that AIX is installed on the first hard drive in the System p5 nodes, and the second hard drive is not used by the operating system. In addition, the system is managed by CSM and the management server is that of AIX from which CSM commands can be issued.

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Configuring the dual boot of AIX and Linux

The following steps should be taken to install Linux, so that it can dual boot with AIX. Please take caution and follow all instructions. If you are not familiar with the above requirements, please do not proceed with the steps outlined below.

Step 1

If you have not done so already, use the HMC to create a logical partition (LPAR) profile for the AIX installation. Make sure to include all adapters currently used by the existing AIX configuration. Note that this should exclude the second hard drive and must include all processors and memory resources.

Step 2

Create a second LPAR profile to be used for the Linux installation. The profile should include the second hard drive and all processors and memory resources. Note that this profile should exclude all adapters that can prevent booting into Linux. Make note that the LPAR ID for this profile should be set to 2; the AIX profile should be 1. This information is necessary for proper control of the profiles during LPAR activation using either the AIX or Linux management server.

Step 3

After creating the profiles, test that the nodes can be booted to either partition. Shut down the AIX operating system, power off the AIX partition, and activate the Linux partition using the HMC. The node should fail to boot from the second hard drive. Reboot into AIX by deactivating the Linux partition and reactivating the AIX partition.

Step 4

Run the CSM lsnode –F command on the AIX management server to capture the existing information stored in the CSM database for the nodes. Copy this information to a file and transfer it to the Linux management server.

Step 5

To continue, you must follow the instructions in the CSM Planning and Installation Guide (see Resources) for adding nodes to the cluster. Before adding nodes to the CSM database, edit and modify the information obtained from the AIX CSM database. You should modify the following attributes of each node before defining them to the CSM database:

1. InstallAdapterMacaddr = 00:0D:60:F4:28:D4 (The address should be colon-separated or CSM retrieves the installation adapter MAC address again for you.)
2. InstallDistributionName =
3. InstallDistributionVersion =
4. InstallMethod =
5. InstallOSName =
6. InstallPkgArchitecture = ppc64
7. InstallServiceLevel =
8. InstallTemplate =
9. InstallDisk=/dev/sdb
   (WARNING: In order to prevent damage to your existing AIX installation, you must add the installation disk entry to the CSM database for all nodes.
   In this case, the Linux operating system sees two hard drives (/dev/sda and /dev/sdb). We assume AIX is installed on /dev/sda, which makes /dev/sdb available to install Linux. By default, the Linux installation program chooses /dev/sda. You must either create your own installation template file and point it to the second hard drive, or use the CSM default installation template file with the entry configured in the CSM database.
10. LParID = 2 (This must be set to 2.)

Step 6

After modifying the nodes definition file, use the CSM definenode command with the -f option to add the nodes to the CSM database.

Step 7

Check the power status of the nodes by running the CSM rpower command from the Linux management server.

Step 8

Power off a node from the Linux management server and power it back on. The node should not have booted into AIX. You can now power off the node again.

Step 9

Power on the node from the AIX management server. The node should boot directly into AIX.

Step 10

Once the simple test completes correctly, proceed to install Linux by first shutting down and powering off all existing AIX partitions using the HMC or the CSM rpower command from the AIX management server.

Step 11

Activate all Linux partitions by using the Linux management server, ensuring that no nodes boot into AIX. If a node does boot into AIX, recheck your LPAR profiles and the node information stored in the CSM database.

Step 12

Install Linux by following the instructions in the CSM Planning and Installation Guide (see Resources).

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Switching between AIX and Linux

The easiest way to switch from one operating system to the next is to first shut down the currently running operating system. For instance, follow the correct procedure and use the shutdown command to bring the operating system to a halt. Use the CSM rpower command on the AIX or Linux management server to power off the previously managed nodes. Switch to the desired management server for the operating system to be booted and issue the CSM rpower command to power on and activate the partition for the specific operating system. Another approach is to use the HMC to locate the LPAR, and then right-click using the mouse to activate the partition.

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Conclusion: Follow steps closely

The instructions just provided assume you have some experience with Linux, AIX, HMC, and CSM. It is critical that you perform all necessary steps before doing the actual installation of Linux on the second hard drive in your System p5 cluster. Failure to carry out the pre-verification steps might result in loss of data and possible damage to your AIX installation.

Resources

• Dual boot Linux and AIX: Learn how to develop in both the Linux and AIX operating environments.
  
  
• Cluster System Management (CSM): Reference the CSM Planning and Installation Guide to review installation and configuration instructions.
  
  
• IBM System p5 library: Find more helpful information in the IBM System p5 library.
  
  

About the authors

Lerone LaTouche is an Advisory Software Engineer working for IBM in the System p5 clusters system test area. Prior to joining IBM, he served eight years in the U.S. Army as an electrician. He is a certified specialist on IBM System p5 (formerly pSeries), AIX systems, and a Red Hat Certified Engineer (RHCE). His area of technical expertise includes building clusters for high-performance computing and technical applications on IBM System p5 and System x (formerly xSeries®) servers. He holds a Bachelor of Science in Computer Science from St. John’s University in Jamaica, New York and a Master of Science in Computer Science from Marist College in Poughkeepsie, New York. You can contact him at latouche@us.ibm.com.

Richard Humphries is a Staff Software Engineer working for IBM at the Poughkeepsie New York Lab. He is responsible for the installation and maintenance of the System p5 Development and Test systems at the lab. He joined IBM in 1981 at the Kingston New York Lab. You can contact him at richardh@us.ibm.com.

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Table of contents

• Introduction: Make the most of hardware resources
• Scenario, prerequisites, requirements
• Preparing to dual boot AIX and Linux
• Configuring the dual boot of AIX and Linux
• Switching between AIX and Linux
• Conclusion: Follow steps closely
• Resources
• About the authors
• Comments

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