Understanding and Planning

This chapter describes what WPAR technology is and how it can be implemented
to work in your IT environment. The chapter is designed to provide system
architects and system administrators the level of knowledge required to plan the
deployment of WPARs in their IT infrastructure.
This chapter will discusses high level positing of WPARs and how it complements
and works with the powerful suite of products for virtualization, high availability
and server consolidation in System p, while helping to provide a higher level of
service to the applications and ultimately the end user of these ever growing and
changing environments. This chapter includes the following sections:
2.1, “High-level planning information” on page 20
2.2, “General considerations” on page 21
2.3, “Global environment considerations” on page 26
2.4, “Application WPARs” on page 27
2.5, “System WPARs” on page 28
2.6, “WPAR mobility.” on page 31
2.7, “WPAR and LPAR comparison” on page 36
2
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20 Workload Partitions in IBM AIX Version 6.1
2.1 High-level planning information
The WPAR technology is purely software based. It can therefore be deployed on
any hardware platform that supports AIX 6:
IBM eServer™ pSeries with POWER4 processors
IBM System p
IBM BladeCenter® JS21 with PPC 970 processors
The WPAR offering consists of two parts:
1. IBM AIX Version 6.1 contains the base support for WPAR technology. This
includes creation and management of both application and system workload
partitions within the LPAR where AIX 6 is installed. AIX provide WPAR
support and management through the AIX command line interface and SMIT
menus.
2. IBM Workload Partitions Manager for AIX is a optional separately installable
licensed program product that supports more advanced features:
– Graphical User Interface including wizards for most management activity.
– Management of multiple WPARs on multiple servers from a single point of
control
– Enablement for WPAR mobility
– Automated and policy-based WPAR mobility.
The decision to use WPAR technology depends on the potential benefits that this
technology can yield to a specific user environment. These benefits have been
described in Section 1.5, “When to use workload partitions” on page 13.
Once the decision to use WPAR has been taken, the planning activity consists
then in deciding:
which is the best suited workload partitions type: application to system
WPARS?
if application mobility will be required?
The answer to these questions have technical consequences that are described
in the following sections.
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2.2 General considerations
The WPAR provides isolation of software services, applications and
administration utilizing flexible software-defined boundaries within a single
instance of the AIX 6.1 operating system (Global). When building a WPAR from
the command line you can configure and start it within a few minutes.
This technology presents system administrators with new planning challenges
concerning network, filesystems and OS versions. Networks aliases, shared or
NFS filesystems, and kernel unicity require a different approach to planning of
applications deployment.
2.2.1 Networking
When planning for networks, one must understand how to get the most of this
technology. Using alias decreases the number of adapters needed for
communications but implies a careful planning of bandwidth utilization, since
several WPARs may share the same adapter.
NFS is a prerequisite to the WPAR mobility functionality. Three components are
involved in NFS communications for WPAR mobility:
the name and IP address of the global environment,
the name and IP address of the WPAR
and the name and IP address of the NFS server.
Since they all play a role in this communication they all must know each other.
Preferably put them all in the same subnet. For more detailed explanations check
Chapter 6, “IBM WPAR Manager for AIX” on page 125.
2.2.2 Deployment of the WPAR manager
The WPAR Manager provides a central systems management solution by
providing a set of web-based systems management tools and tasks simplifying
the management of a customer server and WPAR infrastructure.
The WPAR Manager offers infrastructure resource optimization, service
performance optimization and service availability optimization tools. Specific
features of the Workload Partition Manager include, centralized, single point of
administrative control for managing both system and application WPARs,
browser-based GUI for dynamic resource management, system and application
level workload management through WPARs, provide Role-based views and
tasks, dynamic allocation/reallocation and configuration of virtual servers,
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22 Workload Partitions in IBM AIX Version 6.1
storage, network, and non-interruptive maintenance zero downtime for server
fixes and upgrades through virtual server relocation
Using the WPAR Manager involves three roles:
– A WPAR Management Server which is a java application running in an AIX
server. This can be a stand alone server or a an LPAR in a shared physical
server. (dedicated or micropartition).
– The WPAR Management clients which are installed in each LPAR where
WPAR are planned to be deployed and communicates with the WPAR
Management Server
– The WPAR Manager User Interface is a light-weight browser-supported
interface to the WPAR Management Server. The interface can be provided
by any web browser with an IP connection to the WPAR Management
Server. The UI allows for display of information that has been collected
through the agents, and also provides management capability such as
creation, deletion, relocation of WPARs.
Figure 2-1 shows where the components of the WPAR manager execute.
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Figure 2-1 Workload Partitions (WPARs) running in POWER4, 5, 5+, or 6 nodes
When planning the deployment of WPAR Manager components on different
LPARS and workstation, the network firewalls must be configured to allow traffic
to the specific ports listed on Figure 2-2.
Ports 14080 and 14443 are used for communication between the system
administrator workstation and the WPAR Manager.
Note: This figure contains the default value of ports used by the WPAR
Manager. The system administrator can modify these values when configuring
the WPAR Manager.
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24 Workload Partitions in IBM AIX Version 6.1
Ports 9510, 9511, 9512 and 9513 are used for communications between the
agents and managers.
Figure 2-2 TCPIP ports to configure on firewall to use the WPAR manager
2.2.3 Software prerequisites
Having a single instance of AIX simplifies the installation and general
administration of the WPARs. Software is installed once and used many times in
many WPARs. Although totally isolated from each other, these WPARs use the
same AIX kernel instance. This means that all WPARs use the exact same level
of AIX. When planning for WPARs, one must make sure that all applications
software support the level of AIX of the global environment. More important, plan
for the future. Updating or upgrading AIX in the global environment means
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updating or upgrading AIX in all hosted WPARs environment. If you have an
application that needs a specific version of AIX and cannot be updated, move it
to a different LPAR so that it does not prevent the other WPARs from updating.
2.2.4 File system considerations
System WPARs created with the default options have shared read-only /usr and
/opt filesystems. This speeds up the creation, installation and updating of WPARs
and also prevents the accidental removal of system software shared with other
WPARs. Having the read-only shared /usr and /opt filesystem may not suit every
applications: some applications are designed to write in the /usr or /opt
filesystems. One solution is to defined the needed application’s writable directory
as a different filesystem and link it to the mountpoint the application
needs.Chapter 5.3.3, “Shared /usr with writable filesystem” on page 98 explains
how a WPAR can have a writable directory under a read-only /usr or /opt.
Another solution is for the application to not use the global environment shared
/usr or /opt filesystems. This solution requires extra disk space because it
duplicates the global environment’s /usr or /opt to WPAR’s private and fully
writable filesystems.
Consolidating many applications within one global environment changes the way
the system administrator manages filesystems. Instead of managing multiple
LPARs, each with a few filesystems, he now manages only one LPAR with many
filesystems. In both case, the overall number of filesystems remains in the same
order of magnitude (although using WPARs slightly reduces this number), but
they are controlled within a single system. By default, a system WPAR has 4
dedicated filesystems, and 2 shared read-only and the /proc filesystem. For
example, deploying 200 system WPARs in one global environment will result by
default in a global environment with 800 separate filesystems, and 1200 mount
points in the /proc pseudo-filesystems. The WPAR technology provides an option
to reduce this number of filesystems. Instead of using the default filesystem
creation option, the system administrator can choose to create one single
filesystem per WPAR, as described in Chapter 5.1.4, “Creating WPARs:
advanced options” on page 75. Basically, this solution creates only one real
filesystem (the root “/” filesystem) for the WPAR, and subtrees /var, /tmp, /home
are just created as subdirectories of the “/” filesystem, instead of real filesystems
as they usually are in AIX instances and default system WPAR
Filesystems of each system WPAR are created in the global environment
directory tree and are mounted under the WPAR base directory. One base
directory is defined per WPAR. The default path of the base directory is
/wpars/. When planning to deploy several system partitions, the
system administrator may want to organize base directory in a different directory
tree organization.
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26 Workload Partitions in IBM AIX Version 6.1
Section 2.4 to 2.6 explains in more details filesystems considerations for
respectively application WPARs, system WPARs and when mobility is used.