Live Application Mobility in AIX 6.1

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Live Application Mobility in AIX 6.1Application Mobility using WPARs

Ken Milberg, Writer/site expert

Summary: The most popular innovation of IBM® AIX® 6.1 is arguably workload partitioning. Workload partitioning allows you to havefewer operating system images on your managed system, which is accomplished by allowing virtualization of operating system resources. LiveApplication Mobility is an important component of workload partitioning and provides for increased availability for workload partitions(WPARs). Simply put, it allows you to move WPARs from one logical partition (LPAR) to another while the WPARs are up and running. Itprovides automatic, policy-based relocation of workload between systems using WPARs. This article explores how and when to use LiveApplication Mobility and how to configure a system and its applications to run it.

Date: 03 Jun 2008Level: IntermediateAlso available in: Chinese

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WPARs, LPARs, and Live Application Mobility

Among other benefits, WPARs allow you to deploy applications more quickly and requires far fewer dedicated hardware resources. In fact,unlike a logical partition (LPAR), no physical resources are actually required to build a WPAR. As most system administrators have come torealize, the biggest disadvantage of LPARs are maintaining multiple images, which goes along with possibly over-committing expensivehardware resources, such as CPU and RAM. In other words, while partitioning helps you consolidate and virtualize hardware within a singlebox, operating system virtualization through WPAR technology goes one step further and allows for an even more granular approach of resourcemanagement. It does this by allowing for the sharing of OS images and is clearly the most efficient use of CPU, RAM, and I/O resources.

Rather than a replacement for LPARs, WPARs are a compliment to them and allow one to further virtualize application workloads throughoperating system virtualization. WPARs also work very well with Role-Based Access Control (RBAC), which is another important innovation inAIX 6.1. So what does this have to do with Live Application Mobility?

Live Application Mobility allows you to relocate running WPARs from one LPAR to another. While Sun may have a similar concept with itszone-based strategy, it does not provide for a hot migration of running applications. Of all the UNIX®-based systems, only the IBM AIX OS hasthis important innovation. The way it works is that it uses features such as checkpointing to move the actual running partitions. The checkpointsaves and validates the status of the current application and then starts its back up on the other LPAR in this saved state. Do you still need HighAvailability solutions such as HACMP if you will be using this feature? Absolutely. It's important to make the distinction that Live ApplicationMobility provides for increased availability during scheduled outages, not unscheduled outages. One needs to actively use WPAR manager orthe command line interface to initiate the movement of the WPARs; it is not automatic. Live Application Mobility is actually an optional featurethat is enabled within the WPAR manager component. What's the difference between partition mobility and Live Application Mobility? Partitionmobility is a feature of Power6™ that allows you to migrate entire AIX or Linux® LPARs from one physical server to another. It does notrequire AIX 6.1 or WPARs. This feature helps when scheduling downtime for entire frames.

If you need to take an entire managed system off-line, you can move its partitions to another server. It also allows you to balance workloads andresources by allowing you to move LPARs to different physical servers. Live Application Mobility is an innovation of AIX 6.1 alone and is acomponent of its WPAR strategy, allowing you to move workloads rather than entire partitions. The actual target WPARs can be a differentserver, though it doesn't have to be. It is more flexible, as you can use it on environments where you have a mixed physical architecture: Power5and Power6. It moves applications away from systems that require scheduled downtime for maintenance. It can also be used to improveperformance by moving workloads from stressed out servers to less overtaxed ones. Further, it can help provide energy savings by moving theworkload around in such a way as to allow a physical server to literally sleep during non-peak periods. The table below shows some basicdifferences between Live Application Mobility and Partition Mobility.

Table 1. Differences between Live Application Mobility and Partition MobilityTYPE Live Application Mobility Live Partition Mobility

OS AIX 6.1 Linux, AIX 5.3, AIX 6.1

Hardware PowerPC® 970, POWER4™, 5™, 6™ Power6

Granularity WPARs LPARs

Live Application Mobility -- Configuration challenges

Live Application Mobility in AIX 6.1 http://www.ibm.com/developerworks/aix/library/au-aix61mobility/

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This section looks at how to configure Live Application Mobility.

There are two ways to configure Live Application Mobility. The first is by using the WPAR manager (part of the IBM System Director family)and the second is using the command line. IBM strongly suggests you use the WPAR manager, and having used both, I would say it's simplerand much more powerful to use the manager. Furthermore, it performs certain compatibility tests between both the source and globalenvironments, which are just not provided from the command line. IBM goes as far as to say: "Using the WPAR manager is therefore the onlyrecommended way to perform a WPAR relocation" (see Resources for a link). That was enough for me not to even consider demonstratingmoving WPARs around using the command line; however, if you are so inclined to experiment, the command line tools include the followingcommands:

chkptwpar -- This is the command that creates a snapshot of all the tasks in a WPAR.killwpar -- This command kills all tasks belonging to a paused WPAR.restartwpar -- This command creates the workload partition from the checkpointable state.resumewpar -- This command resumes execution of a paused or frozen WPAR.

The WPAR manager uses a browser-based interface that allows for the management of the WPARs from literally any platform. It is designed tomanage WPARs and provides the enablement that allows one to use Live Application Mobility. It is also a licensed product, which means itcosts money. It includes a centralized database consisting of DB2® with an agent that needs to be installed on each computer. This is veryhelpful because you do not need to log into the LPAR itself to actually create, configure, and enable Live Application Mobility. It also providesfor policy-based mobility, which can significantly reduce your overall workload.

When planning for Live Application Mobility, it's important to start out by defining your reason behind relocating the WPARs. And once youunderstand the why behind your decision to relocate the WPARs, you'll also need to take into account the workloads on both the source andtarget system. It's one thing to use Live Application Mobility as a tool that will allow you to move an application off of an LPAR whose physicalserver needs maintenance for a couple of hours; it's another issue entirely to use this to improve application performance. When using it for thelatter purpose, you'll need to search for frames that have better CPU and memory resources than the source systems. If your goal for using LiveApplication Mobility is energy management and using it as a server consolidation tool, then resource utilization is not as important.

WPAR manager and Live Application Mobility demo

This section shows how to install WPAR manager and relocate a running WPAR.

First, install the WPAR manager. There are two parts to the process:

Installation of the WPAR manager1.Installation of the agent2.

The agent goes on every system that will be managed by the WPAR manager, while the WPAR manager and centralized database is installed ononly one system. Start by installing the filesets for the WPAR manager (see Listing 1).

Listing 1. Installing the filesets for the WPAR manager

# installp -acqgYXd . wparmgt.mgrName Level Part Event Result-------------------------------------------------------------------------------wparmgt.mgr.rte 1.1.1.0 USR APPLY SUCCESSwparmgt.mgr.rte 1.1.1.0 ROOT APPLY SUCCESSwparmgt.cas.agentmgr 1.3.2.18 USR APPLY SUCCESSwparmgt.cas.agentmgr 1.3.2.18 ROOT APPLY SUCCESStivoli.tivguid 1.3.0.0 USR APPLY SUCCESStivoli.tivguid 1.3.0.0 ROOT APPLY SUCCESS

# installp -acqgYXd . wparmgt.db+-----------------------------------------------------------------------------+ Pre-installation Verification...+-----------------------------------------------------------------------------+Verifying selections...doneVerifying requisites...doneResults...

SUCCESSES--------- Filesets listed in this section passed pre-installation verification and will be installed.

Selected Filesets ----------------- wparmgt.db.db2 1.1.1.0 # Workload Partitions Manager ...

Installation Summary--------------------Name Level Part Event Result-------------------------------------------------------------------------------wparmgt.db.db2 1.1.1.0 USR APPLY SUCCESSwparmgt.db.db2 1.1.1.0 ROOT APPLY SUCCESS


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When the filesets are installed, you need to configure the database: # /opt/IBM/WPAR/manager/db/bin/DBInstall.sh -dbinstallerdir/db2 -dbpassword my_password.

When this is completed, you'll need to configure the database connection between the WPAR Manager and the database, and to define theWPAR Agent registration password. While there are three supported modes to run the WPAR manager configurator, we used the console mode-- the non-GUI version -- for our install. We found this to be the simplest method to use.

Listing 2. Console method for running the WPAR manager configurator

lpar55p682e_pub[/tmp/wparmgr] > /opt/IBM/WPAR/manager/bin/WPMConfig.sh -i consolePreparing CONSOLE Mode Installation...===============================================================================Choose Locale...---------------- 1- Catala 2- Deutsch ->3- English 4- Espanol 5- Francais 6- Italiano 7- Portugues (Brasil)===============================================================================WPAR Manager Configuration Summaryn----------------------------------Click Next to configure WPAR Manager with the following values.Click Cancel to terminate.WPAR Manager Access:Public Port: 14080Secure Port: 14443Database Access:Hostname: lpar55p682e_pubUsername: db2wmgtPassword: ********Service Port: 50000Name: WPARMGTAgent Manager, configure local:Base Port: 9511Public Port: 9513Secure Port: 9512Registration password: ******** ->1- Next 2- CancelENTER THE NUMBER OF THE DESIRED CHOICE, OR PRESS <ENTER> TO ACCEPT THE DEFAULT:1===============================================================================WPAR Configuration Complete---------------------------The configuration of IBM Workload Partitions Manager for AIX has completedsuccessfully.PRESS <ENTER> TO EXIT THE INSTALLER: lpar55p682e_pub[/tmp/wparmgr] >

The final piece is installing and configuring the agent, which must be done on each partition that you want managed by the WPAR manager: #

installp -acqgYXd <MOUNT_POINT> wparmgt.agent.

When the filesets are installed, this command will configure the agent for you: # /opt/IBM/WPAR/agent/bin/configure-agent-yourhostmachine.

When completed, we're ready to point our browser to the IP address where WPAR manager is configured. I was able to use this from a VNCclient after configuring VNServer on the host console or from a standard Firefox browser, even from a PC running Windows®. The latter willwork only if you are on the same network as the WPAR manager.

Figure 1. Pointing the browser to the IP address where the WPAR manager is configured


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After logging in with your root password, you can validate the managed systems. We had two systems, as illustrated in Figure 2.

Figure 2. Validating the managed systems

It is from here, that one adds the WPARs and configures them to be able to be relocatable. You do this by making sure that the filesystems usedare NFS and you also check the option that says "checkpointable."

The steps themselves are fairly clear.

Create a working NFS environment on a defined server1.Create a WPAR using NFS directories, using the -c option allowing for checkpointable, necessary to use Live Application Mobility2.Relocate WPARs.3.

There are several ways to create WPARs. In Figure 3 we used the WPAR manager.

Figure 3. Create WPARs using WPAR manager


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In this example (see Listing 3), we'll create a specification file from the command line using mkwpar. There is also a sample file in /usr/samples/wpars -- called sample.spec -- which you can use as a template.

Listing 3. Use mkwpar to create a specification file

# mkwpar -n app20 -h app20 -N interface=en0 netmask=255.255.192.0 address=172.29.140.243 -r -c -M directory=/vfs=nfs host=lpar32p682e_pub dev=/scratch/app20root -M directory=/home vfs=nfs host=lpar32p682e_pub dev=/scratch/app20home -M directory=/tmp vfs=nfs host=lpar32p682e_pub dev=/scratch/app20tmp -M directory=/var vfs=nfs host=lpar32p682e_pub dev=/scratch/app20var

Now, let's return to the WPAR manager. Regardless of where you create your WPAR, you can relocate your partitions from here as well (seeFigure 4).

Figure 4. Start the process of relocating your partitions

Figure 5 shows that the relocation process is in progress.

Figure 5. The relocation process in progress


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It's important to note that even with the GUI, there will be some challenges in terms of getting everything operational, particularly when youfirst start using the system. We found one interesting bug, when we had used an underscore (_) in the host-name, which kept the WPAR managerfrom being able to locate one of our managed systems. After removing the underscore we of course got everthing working well, which you'veseen in this article.

Summary

In this article, we discussed Live Application Mobility in the context of WPARs and how best to use the system. We defined the differencesbetween Live Application Mobility and Live Partition Mobility. We created WPARs and installed WPAR Manager to help us manage our WPARenvironment. Lastly, we created WPARs for the express purpose of using Live Application Mobility and illustrated how to create and moverunning WPARs from one system to another. It's important to understand that Live Application Mobility does not replace High Availability.While it has several purposes, it is best used when performing scheduling outages, which allows for system maintenance to occur with nodowntime. This is a very real and important innovation of AIX 6.1, which neither Solaris nor HP-UX has at this time.

Resources

Learn

AIX 6 Workload Partition and Live Application Mobility: Read a white paper that introduces WPAR concepts, gives hands-on details toshow ease of use, and provides steps that correctly outline the Live Application Mobility function.

Workload Partitioning (WPAR) in AIX 6.1 (Ken Milber, developerWorks, April 2008): Read an article that shows you how and whenshould you use WPAR along with how to create, configure, and administer workload partitions.

IBM Redbooks: Read Advanced Workload Management: Using Workload Partitions in AIX 6 for detailed information on WPAR.

New to AIX and UNIX?: Visit the "New to AIX and UNIX" page to learn more about AIX and UNIX.

AIX Wiki : A collaborative environment for technical information related to AIX.

Optimizing AIX 5L performance: Tuning network performance, Part 1 (Ken Milberg, developerWorks, November 2007): Read Part 1 of athree-part series on AIX networking, which focuses on the challenges of optimizing network performance.

For a three-part series on memory tuning on AIX, see Optimizing AIX 5L performance: Tuning your memory settings, Part 1 (KenMilberg, developerWorks, June 2007).

Read the IBM whitepaper Improving Database Performance with AIX concurrent I/O.

Learn about AIX memory affinity support from the IBM System p and AIX InfoCenter.

The Redbook, Database Performance Tuning on AIX, is designed to help system designers, system administrators, and databaseadminsitrators design, size, implement, maintain, monitor, and tune a Relational Database Management System (RDMBS) for optimalperformance on AIX.

Get ready to take IBM eServer Certification Study Guide - AIX 5L Performance and System Tuning as part of IBM's certificationprogram.

Read Power to the People; A history of chip making at IBM (developerWorks, December 2005) for coverage of IBM's power architecture.

CPU Monitoring and Tuning (Wayne Huang et al. developerWorks, March, 2002): Read this article to learn how standard AIX tools canhelp you determine CPU bottlenecks.


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For a comprehensive guide about the performance monitoring and tuning tools that are provided with AIX 5L Version 5.3, see the IBMRedbook AIX 5L Practical Performance Tools and Tuning Guide.

Learn what features you can benefit from in AIX 5L Version 5.3, in AIX 5L Version 5.3: What's in it for you? (developerWorks, June2005).

Operating System and Device Management from IBM provides users and system administrators with complete information that can affectyour selection of options when performing such tasks as backing up and restoring the system, managing physical and logical storage, andsizing appropriate paging space.

The AIX 5L Differences Guide Version 5.3 Edition (developerWorks, December 2004) redbook focuses on the differences introduced inAIX 5L Version 5.3 when compared to AIX 5L Version 5.2.

The AIX and UNIX developerWorks zone provides a wealth of information relating to all aspects of AIX systems administration.

Open source: Visit the developerWorks Open source zone for extensive how-to information, tools, and project updates to help you developwith open source technologies, and use them with IBM products.

developerWorks technical events and webcasts: Stay current with developerWorks technical events and webcasts.

Podcasts: Tune in and catch up with IBM technical experts.

Discuss

AIX forumAIX forum for developersCluster Systems ManagementIBM Support Assistant ForumPerformance Tools ForumVirtualization ForumMore AIX and UNIX forums

About the author

Ken Milberg is a technology writer and site expert for Techtarget.com and provides Linux technical information and support atSearchopensource.com. He is also a writer and technical editor for IBM Systems Magazine, Power Systems edition, and a frequent contributorof content for IBM developerWorks. He holds a bachelor's degree in computer and information science, as well as a master's degree intechnology management from the University of Maryland University College. He is the founder and group leader of the N.Y. Metro POWER-AIX/Linux Users Group. Through the years, he has worked for both large and small organizations and has held diverse positions from CIO tosenior AIX engineer. He is currently president and managing consultant for UNIX-Linux Solutions, is a PMI-certified Project ManagementProfessional (PMP), an IBM Certified Advanced Technical Expert (CATE), and is also IBM SCon certified.

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Live Application Mobility in AIX 6.1

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