Workload Partitioning (WPAR) in AIX 6.1

WPAR systems administration and configuration

WPARs are a bold new innovation, implemented within AIX 6.1. It allows administrators to virtualize their operating system, which allows for fewer operating system images on your IBM System p™ partitioned server. Prior to WPARs, you would need to create a new Logical Partition (LPAR) for each new "isolated" environment. This is no longer necessary (with AIX 6.1 only), as there are many circumstances when one can get along fine with multiple WPARs within one LPAR. Why is this important? Every LPAR requires its own operating system image and a certain number of physical resources. While you can virtualize many of these resources, there are still some physical resources that must be allocated to the system. Furthermore, you need to install patches and technology upgrades to each LPAR. Each LPAR requires its own archiving strategy and DR strategy. It also takes some time to create an LPAR; you also need to do this outside of AIX, through a Hardware Management Console (HMC) or the Integrated Virtualization Manager (IVM).

WPARs are much simpler to manage and can actually be created from the AIX command line or through SMIT. LPARs cannot. By far the biggest disadvantage of LPARs is maintaining multiple images, which goes along with possibly over-committing expensive hardware resources, such as CPU and RAM. In other words, while partitioning helps you consolidate and virtualize hardware within a single box, operating system virtualization through WPAR technology goes one step further and allows for an even more granular approach of resource management. It does this by sharing 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 complement to them and allow one to further virtualize application workloads through operating system virtualization. WPARs allow for new applications to be deployed much more quickly, which is an important side-benefit. On the other side of the coin, it's important to understands the limitations of WPARs. For example, each LPAR is a single point of failure for all WPARs that are created within the LPAR. In the event of an LPAR problem (or a scheduled system outage, for that matter), all underlying WPARs will also be affected.

WPARs: How and when to use them

This section further defines the different types of workload partitions and discusses scenarios where WPARs should be used.

As discussed earlier, Workload Partitions (WPARs) are virtualized operating system environments that are created within a single AIX (only supported on AIX 6.1) image. While they may be self-contained in the sense that each WPAR has its own private execution environment with its own filesystems and network addresses, they still run inside the global environment. The global environment -- the actual LPAR -- owns all the physical resources of the logical partition. It is important to also note that the global environment can see all the processes running inside the specific WPARs.

There are two types of WPARs: system workload partitions and application workload partitions. The system WPAR is much closer to a complete version of AIX. The system WPAR has its own dedicated, completely writable filesystems along with its own inetd and cron. Application WPARs are real, lightweight versions of virtualized OS environments. They are extremely limited and can only run application processes, not system daemons such as inetd or cron. One cannot even define remote access to this environment. These are only temporarily objects; they actually disintegrate when the final process of the application partition ends, and as such, are more geared to execute processes than entire applications. Overall, WPARs have no real dependency on hardware and can even be used on POWER4 systems that do not support IBM's PowerVM (formerly known as APV). For AIX administrators, the huge advantage of WPARs is the flexibility of creating new environments without having to create and manage new AIX partitions. Let's look at some scenarios that call for the use of WPARs.

Application/workload isolation

WPARs are tailor-made for working with test and/or QA and development environments. Most larger organizations have at least three environments for their applications. These include development, test, and production. Some environments have as many as five, including demo/training and stress/integration environments. Let's use an example of a common three-tier application environment: Web, application server, and database server. In the land of the LPARs, in an environment where one has five isolated environments, you would need to create 15 LPARs. This is where the WPAR has the most value. In this environment, we would need to create just five LPARs. How is that?

In Table 1, we have five different environments, consisting of a Web server, an application server, and a database server. If we wanted to isolate our environments, the only way to do this would be through logical partitioning. That would involve architecting 15 logical partitions. Of course, we could run some of our Web, application, and database on one LPAR, but if we did that, how would we be able to really mimic our production environments (which would run on separate partitions)? In today's world of 99.9% availability, it is extremely common to give each application environment its own home. With WPARs, we can now do that, without having separate AIX images.

Table 1. Web portal -- LPARs only
Development (3 lpars)Demo/Training (3 lpars)Test (3 lpars)Pre-Prod (3 lpars)Production (3 lpars)

Table 2 illustrates how that is done. Each environment would have its own LPAR, with three WPARs created within each LPAR. Now let's imagine if we had four Web servers, two application servers, and two database servers supporting this environment. Yikes! AIX administrators supporting Fortune 500 companies know what I'm talking about. It can be a nightmare maintaining all these environments. WPARs dramatically simplify the overall work-effort involved in administrating this environment, while at the same time minimizing the expense of having to assign physical resources to logical partitions.

Table 2. Web portal -- WPARs inside of LPARs
Development 1 LPAR, 3 WPARsDemo/Training 1 LPAR, 3 WPARsTest 1 LPAR, 3 WPARsPre-Prod 1 LPAR, 3 WPARsProduction 1 LPAR, 3 WPARs
1. Dwaparapp012.Trwpapp013.Tstwparapp014.Ppapp015.Papp01
1. Dwparora012.Trwparora013.Tstwparora014.Ppwparora015.Pora01

Playing nicely in the sandbox

In virtually every environment I've managed, my staff has begged to have sandbox environments in which to work. These environments would be used only by the systems administrators. It is here that administrators have the opportunity to install new software, test out new patches, install new technology levels, and generally be free to break the system without any effect to the business. Unfortunately, it is always the sandbox that is the first environment that must be given up when a new application needs to be deployed. With WPARs, you can quickly create an isolated environment in which to play. While my preference is to have several WPAR sandboxes within an overall LPAR sandbox, each of these owned by a different administrator, this now becomes less of a luxury than it used to be. Looking at this from another perspective, these WPARs are the training ground for new administrators to learn and practice their craft on. With WPARs, they can now be managed much more efficiently and created without having to assign dedicated devices to them.

Quickly testing an application

The application WPAR can be created in just a few seconds. What better way is there to quickly troubleshoot an application or wayward process? As these are temporary resources, they are destroyed as soon as they end, simplifying the manageability of these partitions.

WPARS: When not to use them

This section discusses situations and scenarios where you may not want to use WPARs.


As stated previously, WPAR processes can be seen by the global environment from the central LPAR. If you are running a highly secure type of system, this may be a problem for you from a security standpoint. Further, the root administrator of your LPAR will now have access to your workload partition, possibly compromising the security that the application may require.


Each WPAR within LPAR is now using the same system resources of the LPAR. You need to be that much more careful when architecting your system and also when stress testing the system. For example, if you're running a performance benchmark on your pre-production system after a new build has been deployed and there are some developers working on the application server while you are testing your database, this will all be done within one LPAR sharing the same resources. Your teams will all need to understand that there will be competing resources now for the same product.


If you are in an environment where it is very difficult to bring a system down, it's important to note that when performing maintenance on an LPAR that every WPAR defined will be affected. At the same time, if there is a system panic and AIX crashes, every WPAR has now been brought down. From this standpoint, LPARs without WPARs can provide increased availability across your environment, albeit at a cost that may be prohibitive.


I'm extremely conservative when it comes to production. I like to run each tier in production within its own logical partition. I do this because I like the granularity and complete OS isolation that LPARs provide, without having multiple environments (Web, applicatoin, and database) to worry about.

Physical devices

Physical devices are not supported within a WPAR. While there is a way to export devices, this can be a big problem for applications that require non-exportable devices. In this case, they would be restricted to only running in the global environment. For example, Oracle RAC is not supported using Solaris zones because of this limitation, and should not work in a WPAR environment for the very same reason.

Creating, configuring, and administering WPARs

This section creates, configures, and administers WPARs, both system and application.

System WPARs

The mkwpar command creates the WPAR, installs the filesystems, and prepares the system (see Listing 1). It also synchronizes the root section of the installed software.

Listing 1. The mkwpar command
lpar5ml162f_pub[/] > mkwpar -n devpayrollWPAR01
mkwpar: Creating file systems...

<< End of Success Section >>

  241  Selected to be installed, of which:
      241  Passed pre-installation verification
  241  Total to be installed

                         Installing Software...

Filesets processed:  6 of 241  (Total time:  2 secs).

installp:  APPLYING software for:
Filesets processed:  7 of 241  (Total time:  3 secs).
installp:  APPLYING software for:
Filesets processed:  8 of 241  (Total time:  3 secs).
installp:  APPLYING software for:
Filesets processed:  9 of 241  (Total time:  3 secs).
installp:  APPLYING software for:
Filesets processed:  10 of 241  (Total time:  4 secs).
installp:  APPLYING software for:
Filesets processed:  12 of 241  (Total time:  4 secs).
installp:  APPLYING software for:

Workload partition devpayrollWPAR01 created successfully.
mkwpar: 0960-390 To start the workload partition, execute the 
following as root: startwpar [-v] devpayrollWPAR01

Depending on the type of system you are using, this generally takes between two and four minutes. It took me two minutes and 40 seconds, installing 241 filesets on a one-CPU POWER5 processor running at 1654 MHz. To check the status of the WPAR, use the lswpar command (see Listing 2).

Listing 2. Use the lswpar command to check the status of the WPAR
lpar5ml162f_pub[/] > lswpar
Name              State  Type  Hostname          Directory
MyTestWpar1       A      S     MyTestWpar1       /wpars/MyTestWpar1
MyTestWpar2       A      S     MyTestWpar2       /wpars/MyTestWpar2
devpayrollWPAR01  D      S     devpayrollWPAR01  /wpars/devpayrollWPAR01

In this case, it is still in what is called the "defined state." We'll need to use the startwpar command to make it active (see Listing 3).

Listing 3. Using the startwpar command
lpar5ml162f_pub[/] > startwpar -v devpayrollWPAR01
Starting workload partition devpayrollWPAR01.
Mounting all workload partition file systems.
Mounting /wpars/devpayrollWPAR01
Mounting /wpars/devpayrollWPAR01/home
Mounting /wpars/devpayrollWPAR01/opt
Mounting /wpars/devpayrollWPAR01/proc
Mounting /wpars/devpayrollWPAR01/tmp
Mounting /wpars/devpayrollWPAR01/usr
Mounting /wpars/devpayrollWPAR01/var
Loading workload partition.
$corral_t = {
              'name' => 'devpayrollWPAR01',
              'wlm_cpu' => [
              'path' => '/wpars/devpayrollWPAR01',
              'hostname' => 'devpayrollWPAR01',
              'wlm_procVirtMem' => [
              'wlm_mem' => [
              'key' => 3,
              'vips' => [],
              'wlm_rset' => undef,
              'opts' => 4,
              'id' => 0
Exporting workload partition devices.
Starting workload partition subsystem cor_devpayrollWPAR01.
0513-059 The cor_devpayrollWPAR01 Subsystem has been started. Subsystem PID is 753708.
Verifying workload partition startup.
Return Status = SUCCESS.
lpar5ml162f_pub[/] >

You can now see that is it is in an active state (see Listing 4)

Listing 4. The WPAR is in an active state
lpar5ml162f_pub[/] > lswpar
Name              State  Type  Hostname          Directory
MyTestWpar1       A      S     MyTestWpar1       /wpars/MyTestWpar1
MyTestWpar2       A      S     MyTestWpar2       /wpars/MyTestWpar2
devpayrollWPAR01  A      S     devpayrollWPAR01  /wpars/devpayrollWPAR01

To login, we'll use the clogin command and our hostname for the WPAR. 

Let's login: lpar5ml162f_pub[/] > clogin devpayrollWPAR01
*                                                                             *
*                                                                             *
*  Welcome to AIX Version 6.1!                                                *
*                                                                             *
*                                                                             *
*  Please see the README file in /usr/lpp/bos for information pertinent to    *
*  this release of the AIX Operating System.                                  *
*                                                                             *
*                                                                             *

Let's run some standard AIX commands (see Listing 5).

Listing 5. Some standard AIX commands
# hostname
# w
  10:59AM   up 13 mins,  1 user,  load average: 0.00, 0.00, 0.00
User     tty          login@       idle      JCPU      PCPU what
root     Global      10:59AM          1         0         0 -
# whoami
# ps -ef
     UID    PID   PPID   C    STIME    TTY  TIME CMD
    root 258064 573578   0 10:47:42      -  0:00 /usr/sbin/sshd
    root 340006 573578   0 10:47:55      -  0:00 /usr/sbin/rsct/bin/IBM.Servic
    root 356468 573578   0 10:47:56      -  0:00 /usr/sbin/rsct/bin/IBM.AuditR
    root 421948 573578   0 10:47:41      -  0:00 /usr/sbin/rpc.lockd -d 0
    root 471122      1   0 10:47:23      -  0:00 /usr/lib/errdemon
    root 504032 573578   0 10:47:42      -  0:00 /usr/dt/bin/dtlogin
    root 508124 643204  28 11:00:15      ?  0:00 ps -ef
    root 512114 573578   0 10:47:39      -  0:00 /usr/sbin/portmap
    root 561344 573578   0 10:47:56      -  0:00 /usr/sbin/rsct/bin/IBM.CSMAge
    root 573578      1   0 10:47:33      -  0:02 /usr/sbin/srcmstr
    root 602286      1   0 10:47:41      -  0:00 /usr/sbin/cron
    root 606358 573578   0 10:47:41      -  0:00 /usr/sbin/qdaemon
    root 630928      1   0 10:59:02      ?  0:00 clogin devpayrollWPAR01
    root 635076 573578   0 10:47:39      -  0:00 sendmail: accepting connectio
    root 643204 630928   0 10:59:02      ?  0:00 -ksh
    root 651276 573578   0 10:47:39      -  0:00 /usr/sbin/biod 6
    root 655560 573578   0 10:47:41      -  0:00 /usr/sbin/writesrv
    root 737494 573578   0 10:47:54      -  0:00 /usr/sbin/rsct/bin/rmcd -a IB
    root 741406 573578   0 10:47:39      -  0:00 /usr/sbin/inetd
    root 749714 573578   0 10:47:38      -  0:00 /usr/sbin/syslogd
    root      1      0   0 10:47:21      -  0:00 /etc/init

Your systems administrator can start and stop processes from the WPAR using the SRC or from the command line, just as they would from the global environment. As the Global (LPAR) system administrator, you will note that a WPAR has lots of filesystems. The WPAR environment is created under /wpars (see Listing 6).

Listing 6. Creating the WPAR environment under /wpars
lpar5ml162f_pub[/wpars/devpayrollWPAR01/wpars] > hostname
# df -k
Filesystem    1024-blocks      Free %Used    Iused %Iused Mounted on
/dev/hd4           131072     19472   86%     8278    62% /
/dev/hd2          3538944    150480   96%    91842    70% /usr
/dev/hd9var        262144    246796    6%      522     1% /var
/dev/hd3           262144    259540    1%       56     1% /tmp
/dev/hd1           131072    130688    1%        8     1% /home
/dev/hd11admin      131072    130708    1%        5     1% /admin
/proc                   -         -    -         -     -  /proc
/dev/hd10opt       262144    119804   55%     3048    11% /opt
/dev/fslv12        131072    103476   22%     2244     9% /wpars/devpayrollWPAR01/ora01
/dev/fslv13        131072    128660    2%        5     1% /wpars/devpayrollWPAR01/home
/opt               262144    119804   55%     3048    11% /wpars/devpayrollWPAR01/opt
/proc                   -         -    -         -     -  /wpars/devpayrollWPAR01/proc
/dev/fslv14        131072    128424    3%        9     1% /wpars/devpayrollWPAR01/tmp
/usr              3538944    150480   96%    91842    70% /wpars/devpayrollWPAR01/usr
/dev/fslv15        131072    116448   12%      370     2% /wpars/devpayrollWPAR01/var

Here is the view from the WPAR

# hostname
# df -k
Filesystem    1024-blocks      Free %Used    Iused %Iused Mounted on
/dev/fslv12        131072    103476   22%     2244     9% /
/dev/fslv13        131072    128660    2%        5     1% /home
/opt               262144    119804   55%     3048    11% /opt
/proc                   -         -    -         -     -  /proc
/dev/fslv14        131072    128424    3%        9     1% /tmp
/usr              3538944    150480   96%    91842    70% /usr
/dev/fslv15        131072    116448   12%      370     2% /var

Creating filesystems

Let's turn our attention back to the global environment. Let's create a filesystem through SMIT. You cannot create a f/s or volume group from the WPAR, only from the global environment (LPAR).

We need to make sure that the full path of the filesystem (including the WPAR path) is specified (see Figure 1).

Figure 1. The full path of the filesystem is specific in SMIT
The full path of the filesystem is specific in SMIT
The full path of the filesystem is specific in SMIT

Figure 2 shows the the file system has been created successfully.

Figure 2. The file system has been created successfully
The file system has been created successfully
The file system has been created successfully

After it's successfully created, you'll need to make one minor change to the filesystem: the mount group needs to be explicitly defined (see Figure 3). Note that this step is not necessary when using the command line to create the filesystem: # smit chjfs2.

Figure 3. Explicitly defining the mount group
Explicitly defining the mount group
Explicitly defining the mount group

Now let's turn back to the WPAR, where you'll create the mountpoint and mount the newly created filesystem (see Listing 7).

Listing 7. Creating the mountpoint and mounting the filesystem
# mkdir ora
# pwd
# mount ora /ora01
# df -k
Filesystem    1024-blocks      Free %Used    Iused %Iused Mounted on
/dev/fslv12        131072    103444   22%     2246     9% /
/dev/fslv13        131072    128660    2%        5     1% /home
/opt               262144    119804   55%     3048    11% /opt
/proc                   -         -    -         -     -  /proc
/dev/fslv14        131072    128424    3%        9     1% /tmp
/usr              3538944    150480   96%    91842    70% /usr
/dev/fslv15        131072    116448   12%      370     2% /var
/ora               131072    103444   22%     2246     9% /ora01

Note that you also cannot increase the size of a filesystem from the WPAR, only from the global environment. You also cannot serve NFS filesystems from within the WPAR; only NFS clients are supported.


Remember, there are no physical devices in a WPAR. When backing up the WPAR environment, you need to use the savewpar command, again from the global environment.

Listing 8. Using the savewpar command
lpar5ml162f_pub[/wpars/devpayrollWPAR01/wpars] > savewpar 
                   -f /admin/payroll.backup devpayrollWPAR01

Creating information file for workload partition devpayrollWPAR01.

Creating list of files to back up.
Backing up 2829 files
2829 of 2829 files (100%)
0512-038 savewpar: Backup Completed Successfully.
lpar5ml162f_pub[/wpars/devpayrollWPAR01/wpars] >

You can restore using the restwpar command.

Users and groups

You can maintain users and groups within the WPAR, either from the command line or through SMIT. You should understand that the root user for this environment does not have access to the global environment, only to the WPAR (see LIsting 9).

Listing 9. Maintaining users and groups within the WPAR
# mkuser test
# mkgroup testing
# hostname
# lsuser
Usage: lsuser [-R load_module] [ -c | -f ] [ -a attr attr ... ] 
                                    { "ALL" | user1,user2 ... }
# lsuser test
test id=204 pgrp=staff groups=staff home=/home/test shell=/usr/bin/ksh 
login=true su=true rlogin=true daemon=true admin=false sugroups=ALL admgroups= 
tpath=nosak ttys=ALL expires=0 auth1=SYSTEM auth2=NONE umask=22 registry=files 
SYSTEM=compat logintimes= loginretries=0 pwdwarntime=0 account_locked=false 
minage=0 maxage=0 maxexpired=-1 minalpha=0 minother=0 mindiff=0 maxrepeats=8 minlen=0 
histexpire=0 histsize=0 pwdchecks= dictionlist= default_roles= fsize=2097151 cpu=-1 
data=262144 stack=65536 core=2097151 rss=65536 nofiles=2000 roles=
# lsgroup testing
testing id=203 admin=false users= registry=files

Now let's turn our attention back to the global environment. You can clearly see in Listing 10 that the user was not created in the global environment, only within that specific WPAR.

Listing 10. The user was not created in the global environment
lpar5ml162f_pub[/wpars/devpayrollWPAR01/wpars] > lsuser test
3004-687 User "test" does not exist.
lpar5ml162f_pub[/wpars/devpayrollWPAR01/wpars] >

WPAR manager

It's worth noting that there is a graphical tool called WPAR manager, which is Java™ based and allows for the centralized management of WPARs (see Figure 4).

Figure 4. WPAR manager
WPAR Manager
WPAR Manager

While a thorough review of this utility is outside the scope of this article, it's definitely worth looking at because using it will increase your ability to manage the overall environment. It will also help you harness innovations such as Workload Partition Manager and WPAR Mobility. Workload Partition Manager allows for resource optimization, allowing you to distribute workloads more efficiently throughout your managed system. WPAR mobility allows you to move running partitions from one frame to another, which increase availability of workloads during scheduled outages.

Application WPARs

To reiterate, an application WPAR is defined as a WPAR that allows an application and/or a process to run inside of it, similar to a wrapper. It is only temporary, not a permanent object, and it will end when the application and/or process ends. To create one, use the wparexec command.

Listing 11. Using the wparexec command to create an application WPAR
lpar5ml162f_pub[/wpars/devpayrollWPAR01/wpars] > wparexec -n templs1 /usr/bin/ls
Starting workload partition templs1.
Mounting all workload partition file systems.
Loading workload partition.
Shutting down all workload partition processes.
lpar5ml162f_pub[/wpars/devpayrollWPAR01/wpars] >

To see how the process works while it is working, you will see the creation of the WPAR (see Listing 12).

Listing 12. Seeing the creation of the WPAR
 lpar5ml162f_pub[/] > lswpar
Name              State  Type  Hostname          Directory
MyTestWpar1       A      S     MyTestWpar1       /wpars/MyTestWpar1
MyTestWpar2       A      S     MyTestWpar2       /wpars/MyTestWpar2
devpayrollWPAR01  A      S     devpayrollWPAR01  /wpars/devpayrollWPAR01
evpayrollWPAR01   D      S     evpayrollWPAR01   /wpars/evpayrollWPAR01
templs1           T      A     templs1           /

When the process completes, it is gone, just as fast as it was created.

Listing 13. The process is gone
lpar5ml162f_pub[/] > lswpar
Name              State  Type  Hostname          Directory
MyTestWpar1       A      S     MyTestWpar1       /wpars/MyTestWpar1
MyTestWpar2       A      S     MyTestWpar2       /wpars/MyTestWpar2
devpayrollWPAR01  A      S     devpayrollWPAR01  /wpars/devpayrollWPAR01
evpayrollWPAR01   D      S     evpayrollWPAR01   /wpars/evpayrollWPAR01
lpar5ml162f_pub[/] >

Truthfully, although it's impressive that you can create application WPARs in a matter of seconds, and it's a feature that Solaris does not have, I think it is most useful for providing additional flexibility for testing purposes.


This article introduced WPARs and discussed the context in which to use them. The article looked at various scenarios in which WPARs should be used. It also discussed the installation, configuration, and administration of WPARs and how they relate to the global (LPAR) environment. You added users, created filesystems, and backed up WPARs. You also introduced utilities such as WPAR manager, which could be used to help manage the WPAR environment. You looked at the different types of WPARs that are available and the limitations of application WPARs compared to system WPARs. You also looked at scenarios in which WPARs may not be considered. The bottom line is that WPARs are an important innovation of AIX 6.1, and used judiciously, can increase your ability to effectively manage your system and reduce cost to the business.

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Zone=AIX and UNIX
ArticleTitle=Workload Partitioning (WPAR) in AIX 6.1